Basra violence erupts after Iraqi PM orders security crackdown

Dozens of injured people were arriving at hospitals as police and military sources said an operation was under way against the Mehdi Army, which is loyal to cleric Moqtada al-Sadr.

A night-time curfew was imposed in the southern city last night, just 24 hours after it was revealed the British withdrawal of troops was being delayed after the increase in rocket attacks.

Iraqi authorities said the curfew from 10pm until 6am would be enforced until further notice.

On a visit to the southern city yesterday, Iraqi PM Nouri al-Maliki said his government had decided to "reimpose stability".

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A witness in the city reported seeing columns of black smoke over northern districts today and hearing the sound of explosions and machinegun fire.

Television pictures showed Iraqi troops running through empty streets and taking cover.

Major Tom Holloway, a spokesman for British forces in Basra, said Mr al-Maliki was in the city to oversee the operation. Troop reinforcements had been sent from across Iraq, he said.

Rival factions of Iraq's Shi'ite majority and criminal gangs are competing for control of Basra, Iraq's second city and gateway to the Gulf, along with its oil fields, which are the source of most government revenues, officials say.

Iraqi oil industry sources said the fields, which exported 1.54 million barrels of oil in February, were operating normally.

Iraqi army Major-General Ali Zaidan, the commander of Iraqi ground forces in the operation, said the offensive started at dawn and would continue "until we achieve our target".

"The target is to wipe out all the outlaws. There were clashes and many outlaws have been killed," Zaidan said.

The operation was launched after Maliki arrived in the city on Monday vowing to reimpose his government's control over the semi-lawless city.

A hospital source said "tens of wounded" were arriving at hospitals with some too busy to accept more casualties.

Basra residents said Tuesday's operation was concentrated in six northern districts where Sadr's powerful Mehdi Army militia is known to have a strong presence.

Harith al-Ithari, the head of Sadr's office in Basra, called for calm and accused the Shi'ite-led government of deliberating targeting Sadrists. Sadr's political bloc pulled out of Maliki's Shi'ite-led government last year.

The British military said no British ground forces were involved in the operation, but warplanes from the U.S.-led coalition were carrying out aerial surveillance.

The deteriorating security situation in Basra has led to concerns that no more British personnel will be withdrawn before 2009.

The force was to have been cut from 4,100 to 2,500 by the end of April, but this will no longer happen.