Clashes broke out between insurgents and Iraqi security forces and a car bomb killed at least two people in Baghdad on Wednesday as the government launched a security clampdown to root out al Qaeda militants.

Gunmen carrying automatic rifles blocked roads with stones and tree trunks and exchanged fire with Iraqi troops in Adhamiya, a Sunni insurgent stronghold that is one of Baghdad's most dangerous areas, a Reuters reporter at the scene said.

Civilians fled the area but there were no immediate reports of casualties. Three Iraqi army tanks were dispatched to Adhamiya. The clashes subsided later on Wednesday.

In northern Baghdad, a car bomb targeting a police patrol killed two people and wounded seven. A Reuters photographer who was 10 meters (yards) from the blast saw a man and a teenager burning amid wreckage after the bomb caused a big fireball.

The clampdown, which included extra checkpoints and Iraqi security patrols backed by tanks and armored vehicles, came a day after President Bush met new Prime Minister Nuri al-Maliki, who is under pressure to rein in violence.

US and Iraqi forces have carried out several such operations in the past but have failed to stem the bloodshed that has killed tens of thousands since the US-led invasion in 2003, and pushed Iraq toward civil war.

Iraqi officials said the operation would involve more than 40,000 Iraqi and US-led forces as part of a sweep to put further pressure on al Qaeda in Iraq following the killing of its leader Abu Musab al-Zarqawi last week in a US air strike.

In a surprise visit to Iraq, Bush, who faces low popularity ratings over a war that has killed nearly 2,500 US troops, told Maliki the fate and future of Iraq was "in your hands."

"The decisions you and your cabinet make will determine as to whether or not your country succeeds, can govern itself, can defend itself, can sustain itself," Bush told Maliki, whose self-styled government of national unity took office last month.

Daily carnage

With a population of seven million, Baghdad has been the scene of daily carnage and kidnappings.

Restoring some security in Baghdad would be a symbolic victory for Maliki, a tough-talking Shi'ite who last week overcame fierce wrangling among his Shi'ite and Sunni coalition partners to fill the key Interior and Defense ministries.

Despite growing domestic unease, Bush has resisted setting a public timetable for the withdrawal of 130,000 American troops, making clear this will depend on the capability of US-trained Iraqi forces to take over security.

Maliki told Bush during his second visit to Iraq since the 2003 war that the Iraqi government was determined to defeat the insurgents so US and other forces could withdraw.

Reuters reporters saw additional army checkpoints backed by armored vehicles in Baghdad's western Mansour district and an Iraqi tank in religiously mixed Amiriya, which has seen frequent clashes between Sunni Arab insurgents and US and Iraqi forces.

American forces were not in sight.

There was little evidence of additional troops in the dangerous, mostly Sunni area of Dora, where the government said it would also focus its security efforts.

As Bush talked to Iraqi leaders in the heavily fortified Green Zone on Tuesday, a Web statement said al Qaeda's new leader in Iraq had vowed to avenge the killing of Zarqawi.

"The day of vengeance is near and your strong towers in the Green Zone will not protect you," said the statement, posted on an Internet site often used by Islamist militants and signed by the new leader Abu Hamza al-Muhajir.

"Tough days ahead "

US and Iraqi officials have hailed the killing of Zarqawi, a Sunni Arab like most guerrillas in Iraq, as a major blow to al Qaeda militants while cautioning it will not end bloodshed.

"There are going to be tough days ahead, and more sacrifice for Americans, as well as Iraqis," Bush told US troops.

"Our military will stay on the offensive. We will continue to hunt down people like Mr. Zarqawi, and bring them to justice," he said to applause.

Iraqi officials billed Wednesday's clampdown as one of the biggest such operations in the last three years.

"It is an operation to step up pressure on al Qaeda in Baghdad," national security adviser Mowaffaq al-Rubaie told state television on Tuesday.

(Chinadaily.com via agencies June 15, 2006)