Car bombs killed 30 people in Iraq yesterday and wounded more than 70 in one of the bloodiest spasms of violence of recent weeks as political leaders closed in on a deal to form a national unity government.

The southern city of Basra was largely calm as British military engineers examined the wreck of a helicopter whose apparent shooting-down was followed by clashes between troops and youths chanting triumphal Shi?ite militia slogans.

At least 21 people were killed and 52 wounded when a suicide bomber detonated a car on a crowded street in the Shi?ite holy city of Kerbala, south of Baghdad, police and doctors said. The effect was devastating.

Around the same time, two cars exploded in the capital. A suicide car bomber hit an Iraqi army patrol in the rebellious, mainly Sunni northern district of Aadhamiya, killing eight people and wounding 15. Soldiers and civilians were among the casualties. Iraqi and US forces had conducted a sweep for Sunni guerrillas in Aadhamiya on Saturday, the US military said.

A second car bomb exploded at a busy intersection close to the offices of a government-funded newspaper in northern Baghdad, killing one civilian and wounding five.

In Kerbala, the police chief told a news conference only two people had died in the bombing. But police and hospital officials who declined to be named stood by their casualty figures and said rescue work was continuing four hours later.

The blast decimated crowds going about their business at the start of the working week, close to a partially built Shi?ite mosque and 500 metres (yards) from the main bus station. A dozen other vehicles burned out as a result of the explosion.

Interior Ministry sources said 42 bodies had been found in the last 24 hours in the capital alone. The figure is in line with levels of violence seen since sectarian bloodshed spiked up after the bombing of a Shi?ite shrine on Feb. 22.

Sunni leaders blame pro-government Shi?ite militias and the Shi?ite-dominated police for some of the sectarian killing. Militia leaders speak of a need to respond to three years of violence by insurgents from the once-dominant Sunni minority. Sectarian bloodshed has prompted warnings Iraq is sliding towards civil war, and added urgency to efforts by political leaders to form a unity government that can reverse the trend.

Nuri al-Maliki, the Shi?ite Islamist nominated as prime minister two weeks ago after months of stalemate following December?s election, says he expects to name a cabinet shortly. Representatives of the majority Shi?ites, Kurds, Sunnis and others were meeting again yesterday. On Saturday, the Shi?ite vice president said he expected a deal ?in the next few days?. Many party leaders were in the Kurdish capital Arbil yesterday, for the inauguration of a new regional government there.

The US military said last week that Sunni Islamist hardliners around al Qaeda figurehead Abu Musab al-Zarqawi were stepping up car bombings and other violence around Baghdad, to derail the efforts to forge a consensus government.

Zarqawi has in the past declared war on Shi?ites, who were oppressed under Saddam Hussein. Attacks in Kerbala and other Shi?ite centres, including a bombing that killed 50 in Kerbala in January, have been characterised by some Iraqi leaders as attempts to provoke Shi?ite militias into all-out warfare.

Slogans against occupation

Iraq?s southern second city, Basra, was calmer yesterday after a curfew and with a heavy security presence after violence greeted the apparent shooting-down of a British military helicopter on Saturday.

Youths chanting slogans in favour of the Mehdi Army militia of anti-occupation Shi?ite cleric Moqtada al-Sadr had thrown rocks and petrol bombs at British troops cordoning off the site. A health service official said five Iraqis had been killed and 42 wounded in the clashes. Defence Secretary Des Browne said up to five Britons died in the crash.

Iraqi police said it had been shot down but there was no British confirmation of this. Browne played down the unrest. He said plans for British troops to leave Iraq would depend on other factors. Iraqi President Talabani wrote to Prime Minister Blair, describing the deaths of those on the helicopter as a ?vile crime?.

Alastair MACDONALD