Iraqi army calls on British air support in Basra

British warplanes have carried out bomb attacks on Shi'ite militia positions in Basra, directly entering the fray for the first time since the Iraqi army began the crackdown in the southern city.

Nouri al-Maliki, the Iraqi prime minister, conceded failure in his bid to crush rebel fighters in Basra today, offering an extended deadline and cash incentives for the surrender of heavy weapons.

As Mr Maliki issued his offer the security forces admitted they had lost control of a major city north of Basra.

The development took the gloss off an announcement by a top commander that offensive operations in the southern city resulted in the deaths of 120 militia fighters.

Witnesses reported that Nasiriyah, north of Basra, had fallen to supporters of Moqtada al-Sadr, a populist cleric.

Baghdad was calm as a curfew imposed at short notice on Thursday night held.

"So far casualties are 120 killed from the enemy and 450 wounded," said Major-General Ali Zaidan, commander of Iraqi ground forces in the Basra operation.

Major Tom Holloway, a spokesman at Basra Airbase said two bombing missions were carried out overnight against specific targets.

In a statement that confirmed he was in negotiations with tribal and religious leaders in the city for a negotiated end to the fighting, Mr Maliki gave the Shi'ite gunmen until April 8 to surrender heavy and medium weapons used against Iraqi army forces in fierce fighting that has engulfed Shi'ite areas across the country since Tuesday.

"All those who have heavy and medium arms, they should surrender them to the security forces and receive money starting from March 28 until April 8," Mr Maliki said in a statement issued by his office in Baghdad.

"We confirm the objectives of the operation in Basra which is to chase illegal elements and to put all the weapons under the control of law.

"These weapons create problems for civilians and their property. The government wants to give a chance to solve the problem without having to call upon the wrath of legal action."

Fighting has raged in other Shi'ite strongholds such as the central city of Kut, Nasiriyah in the south, Hilla and Baghdad's Sadr City.

Mr Maliki, whose armed forces are facing the first major test of their authority, has vowed to pursue the crackdown on Shi'ite gunmen despite protests and mounting casualties.

But the move has put severe strain on a ceasefire imposed by Sadr on his Mahdi Army followers in August.

Basra has become the theatre of a turf war between the Mahdi Army and two rival Shi'ite factions - the powerful Supreme Iraqi Islamic Council (SIIC) of Abdel Aziz al-Hakim and the smaller Fadhila party.

Sadr has not yet called off the ceasefire and has issued statements calling for a "peaceful and political solution to end the crisis", according to a statement released by his office in the holy city of Najaf.