British forces in Basra today said they had blown up the local headquarters of the ruling Ba’ath party, following reports of a popular uprising in the southern Iraqi city last night.

A 2,000lb bomb, known as a Joint Direct Attack Munition (JDAM), smashed through the building and reduced it to rubble, according to GMTV reporter Richard Gaisford, who is embedded with British troops surrounding the city.

Adjoining civilian structures were reportedly left intact.

American F/A-18 Super Hornet warplanes have also dropped satellite-guided bombs on central Basra – the first strikes into the centre of the city aimed at military sites hidden in civilian buildings.

This morning there were conflicting reports of a popular uprising against the Ba’ath leadership. The defence secretary, Geoff Hoon, told BBC Radio 4′s Today programme that there had been an attempted uprising on some scale in Basra.

“Certainly there have been disturbances, local people rising up against the regime … we haven’t witnessed it but we know that that is happening from various sources,” he said.

“There seemed to be an uprising in Basra last night,” a British military spokesman, Group Captain Al Lockwood said today. “We are assessing the situation very carefully to see how we can capitalise on it and how we can assist.”

Gp Capt Lockwood claimed Iraqi civilians started attacking fighters who were defending the city from British forces yesterday.

“Big guns that normally shoot into the sky were turned horizontal and fired into the crowd – that’s what the intelligence reports were [saying],” reported Mr Gaisford.

This morning Al-Jazeera TV reported that all was quiet inside the city, with no apparent signs of an uprising.

In a telephone interview with the Qatar-based channel, Iraqi information minister Mohammed al-Sahhaf denied any uprising in Basra.

“The situation is stable,” he said. “Resistance is continuing and we are teaching them more lessons.”

However, British pool reports described thousands of residents rampaging through the streets in the early evening and setting dozens of buildings on fire.

US defence secretary Donald Rumsfeld reacted cautiously to reports of the unrest, saying he was “reluctant” to encourage uprisings explicitly. “I am very careful about encouraging people to rise up,” he said. “We know there are people in those cities ready to shoot them if they try to rise up.”

But he added: “Anyone who’s engaged in an uprising has a whole lot of courage and I sure hope they’re successful.”

During the 1991 Gulf war, the city’s predominantly Shia Muslim population took up arms against the Iraqi regime, but government forces crushed the rebellion, killing thousands, after US-led forces pulled out of the country.

Last night, British forces at the gates of Basra battled with more than 1,000 Iraqi militia fighters outside the city. The Royal Scots Dragoon Guards are poised for the order to move in and invade, which they expect to come some time in the next 24 hours.

Yesterday, a British army spokesman said British forces staged a raid into the Basra suburb of Az Zubayr and captured a senior Ba’ath party politician, killing 20 of his bodyguards.

He added that armed irregular units were firing at British forces outside the city, and that the Iraqis were apparently using civilians in front of them as human shields.

British forces have distributed leaflets and broadcast announcements to the city’s 1 million inhabitants, telling them that aid is waiting outside the city. Basra’s residents are currently drinking contaminated water following war damage to the city’s main water processing plant.

Military leaders had hoped to avoid entering Basra, for fear of getting bogged down in urban warfare. But tenacious resistance in the city – there are an estimated 1,000 pro-Saddam fighters, plus an unknown number of regular troops – and growing shortages of food and clean water have compelled them to change their strategy.

Aid supplies begin to move in

As British ships prepare to land aid for the stricken city through the port of Umm Qasr, the health threats in Basra appeared dire today. “The humanitarian situation in Basra is difficult, and very, very tense,” said Muin Kassis of the International Committee of the Red Cross (ICRC). The UN Children’s Fund estimates up to 100,000 Basra children under the age of five are at immediate risk of severe disease from the unsafe water, especially life-threatening diarrhoea.

The British naval ship Sir Galahad, carrying 211 tonnes of food and 101 tonnes of bottled water, was today beginning the six-hour journey from the Khor Abdallah estuary to Umm Qasr.

Royal Marine commandos who carried out an overnight sweep around the port say they have enough control over the area to begin sending in ships. Coalition forces are struggling to clear the way for more aid shipments, using dolphins to remove mines from waterways and hunting Iraqi fighters around the port.

Meanwhile, the first sizeable relief convoy today set out from Kuwait in a biting sandstorm, heading across land for Umm Qasr.

“We planned for 30 trucks but we only got seven loaded because of the severe sandstorm,” said EJ Russell of the Humanitarian Operations Centre, a joint US-Kuwaiti agency.

Hundreds of cases of water were stacked on three of the trucks. The rest carried boxes of tuna, crackers, sweets and other food.

Plans to bring supplies to Iraqi civilians have been on hold for days because of fiercer than expected fighting across southern Iraq.

Yesterday, the UN secretary-general, Kofi Annan, warned the US that it is legally responsible for providing relief aid.

Iraqis have about five weeks of food left, according to estimates by the World Food Programme. About 13 million people – 60% of Iraq’s 22 million – are completely dependent on food handouts.

Iraqi TV back on air

Iraqi state television was back on air this morning despite a heavy dawn bombing raid that targeted the country’s national station.

The state channel does not broadcast overnight and had been off the air at the time of the bombing. A Reuters correspondent today reported that the station began broadcasting verses from the Koran at around 0600 GMT as normal this morning, quashing US hopes that Saddam Hussein’s lines of communication with his people had been cut.

The US government has been outraged at Saddam’s use of state television to broadcast shocking pictures of US PoWs and soldiers killed in action. A successful strike on the TV station would have been a significant blow to the Iraqi regime, the US believed.

The raid on Baghdad did, however, appear to have taken out Iraq’s international satellite channel. Monitors in Dubai reported that the satellite has been off the air since the raids began early this morning. Amnesty International today warned that the TV station bombing could be in breach of the Geneva convention.

A new wave of explosions in southern Baghdad were reported at around 0800 GMT this morning, as US-led forces appeared to target Iraqi forces dug in to defend the capital. Visibility continues to be very poor in the city, with high winds, dust storms and plumes of smoke from burning oil pits.

Dawn raids on northern Iraq

Several large explosions were reported in the northern Iraqi city of Mosul this morning, according to Al-Jazeera. Its correspondent in Mosul said air raid sirens had rung out over the city, 240 miles north of the capital, around dawn this morning.

At the same time, US planes also today targeted frontline Iraqi positions in the north of the country near the Kurdish-controlled town of Chamchamal, said a Reuters correspondent in the area.

Chamchamal is about 20 miles east of the key northern city of Kirkuk, which lies in Iraqi controlled territory over the border to the northern no-fly zone. The major oil town has also been a target for US-led bombing raids in recent days.

Troops continue push for Baghdad

US marines continued to push north from the southern Iraqi city of Nassiriya today, shelling suspected Iraqi positions as they did so.

After finally punching through fierce Iraqi resistance from Fedayeen militia units on the Euphrates river yesterday, the forces are laying down barrages of artillery as they move towards Baghdad. Officers said they were prepared for more heavy fighting along the way.

British soldiers named

The two soldiers killed by fire from another British tank in southern Iraq were named today. The Ministry of Defence identified the two tank crew as Corporal Stephen Allbutt, 35, a married father of two, and unmarried Trooper David Clarke, 19.

The men, both from central England, died on Monday night when their Challenger 2 tank fighting Iraqi forces west of Basra was mistakenly targeted by another British tank.

A total of 22 British servicemen are now listed as dead or missing in the Iraq war. Only two have been killed in action. British fatalities for the whole of the 1991 Gulf war totalled 24.

‘Bloodiest battle’ kills hundreds of Iraqi soldiers

Further north, US commanders said today that “large numbers” of Iraqi forces had been killed during a major battle yesterday evening near the town of Najaf, 100 miles south of Baghdad. Iraqi reports of the death toll reaching 750 were this morning unconfirmed.

The US military said the fighting centred around a fierce two-hour battle in the middle of a severe sandstorm, beginning at around 1700 GMT last night. American tanks clashed with Iraqi fighters armed with rocket-propelled grenades, after a dozen or more US tanks became stranded on the far side of a river when Iraqis blew up a bridge they had crossed and more tanks went in to help.

Commanders on the ground gave no information on casualties but said they expected the Iraqi death toll to be “very high”.

Sky television quoted a senior US officer near Najaf who said the Iraqi death toll could be 650. If confirmed, the battle would be by far the bloodiest encounter in six days of fighting. In Washington, the Pentagon said 150 to 300 Iraqis might have been killed and two US tanks were destroyed.

“They did damage a couple of pieces of our gear but we’ve had no reports of casualties on our side,” a spokesman said.