THE battle for Fallujah gathered momentum yesterday as US troops moved into positions on the edge of the city, and Iraqi families fled the most intensive air and artillery bombardment since April’s failed effort to pacify the city.

On the first day of the Muslim holy month of Ramadan, local leaders reported the presence of US tanks on the northern Al-Thirthar road, close to the railway station. More than 1,000 troops, including a US Army battalion and a Marine battalion, with Iraqi special forces, took part in the overnight operation.

The man who had been negotiating peace terms with the Iraqi interim government was said to have been arrested by US soldiers. The headquarters of the US-led multinational force denied that US soldiers had arrested Khalid Hamoud al-Jumailim, Fallujah’s chief negotiator. But a spokesman for the hardline Association of Muslim Scholars told The Times that Mr al Jumaili had been seized at a US checkpoint as he returned from delivering humanitarian aid to refugee families in the village of Amaryat.

The road to Baghdad was blocked by US forces, but local people said that refugees were fleeing to towns and villages outside the bombing zone. “In the battle last April I didn’t leave the city because the bombs were falling only on areas where the fighters were,” said Ahmed Ismail, 32, a shopkeeper who escaped to the village of al-Buissa with his wife and four small children. “But last night they were bombing the entire city, and many families were killed. We are all targets now.

“People assume that the Americans are bombing us to drive a wedge between ordinary people and the guerrillas. They think that we will blame the guerrillas for the bombs — but they only make us more sympathetic.”

An administrator at Fallujah General Hospital said that the bodies of six men had been received and that doctors were treating 16 wounded, including eight women and three children. The true casualty number may be higher: guerrillas often treat their own wounded and bury their own dead.

Loudspeakers at mosques broadcast an appeal to families to leave. The statement added: “If the United States does not desist from its military operation and if they continue to invade, Fallujah will issue a fatwa (proclamation) for jihad all over the country and target anyone collaborating with the Americans.” It urged people to form a human shield at the town’s eastern entrance against any US advance.

The offensive began late on Thursday, after a warning by Iyad Allawi, the Prime Minister, that the city must hand over the Jordanian militant Abu Musab al-Zarqawi. Local leaders say they know nothing of his whereabouts. Al-Zarqawi’s Tawhid wal Jihad group has claimed to be behind many bombings and the beheading of hostages, including Kenneth Bigley, the British engineer.

“They burn houses, they kill women and children, but where is this al-Zarqawi?” an angry cleric said. “Many of the foreign fighters were already blessed with martyrdom and many have left the city,” he said. “Those that remain are very few, and it would be disgraceful and dishonourable for us to hand them over to the US Army since they had come to Fallujah to support us.”

This spring the US Marines attempting to recapture the city were pulled out by order of Washington, to the disgust of their commanders. After that, the assumption was that the Bush Administration would veto any attack on Fallujah until after next month’s presidential election.But with John Kerry gaining on the President in US opinion polls, the White House may be gambling on military successes to boost Bush.

Despite the scale of the new offensive, the US military in Baghdad was cautious. “It is not the beginning of a major offensive,” an official said, adding that terrorists planned to use Ramadan to start attacks.

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