Iraq took control of the central Shiite province of Babil from US forces on Thursday, in what local officials said was further sign of security gains across the war-torn nation.

But shortly before the handover, a suicide bomber rammed his explosives-filled car into the convoy of a Shiite cabinet minister in Baghdad, killing 11 people although the minister emerged unscathed.

Babil, known for its ancient archaelogical treasures but also a string of bloody attacks on Shiite pilgrims in the aftermath of the US-led invasion of 2003, is the 12th of the country's 18 provinces to be transferred by US forces to Baghdad's command.

Local officials hailed the role of former Sunni rebels who joined US forces in fighting al-Qaeda for improving security in the province, whose northern part earned the ominous nickname the Triangle of Death because of the relentless bloodshed.

"Just a year ago this province used to see well over 20 attacks per week and today attacks are down by 80 percent. This is truly remarkable," Lieutenant General Lloyd Austin, the number two commander of US forces in Iraq, said at the handover ceremony in the provincial capital Hilla.

He warned that the enemies of Iraq were still "not defeated" and offered US support to local forces in maintaining stability.

"I am confident that the central government and the provincial government, Sunni and Shiite will work together to ovecome any challenge we may face."

Iraq's national security advisor Mowaffaq al-Rubaie said domestic security forces would also soon take over the nearby province of Wasit from the US military.

"I want to declare from Babil that Iraq will take over Wasit in the next few days and we hope to complete the transfer of the remaining provinces in the near future," Rubaie said.

"Today the security forces of Babil are self-reliant and we are proud to take over Babil from US forces."

The transfer came just two days after a bloody firefight in the province between insurgents and Sunni tribesmen that left 15 people dead and scores more wounded.

Babil governor Salem al-Saleh Meslmawe nevertheless said the province was now stable.

"The Awakening forces played a big role for the stability and to kick out Al-Qaeda," he said, referring to the former Sunni insurgents also known as the Sons of Iraq who turned against the jihadists.

With the transfer of the province, American forces will retreat to their bases and become involved in security operations only at the request of the provincial governor.

Baghdad, Diyala, Salaheddin, Nineveh, Kirkuk and Wasit remain under US control.

Babil is home to 1.3 million Iraqis and rich archaeological treasures and was the site of the legendary Hanging Gardens of Babylon, one of the ancient Seven Wonders of the World.

But it was ripped apart by violence after the US-led invasion with frequent sectarian attacks on Shiite pilgrims by Sunni insurgents and Al-Qaeda jihadists.

In the bloodiest attack in March 2007, a suicide bombing in Hilla killed at least 117 pilgrims and wounded nearly 200.

After the invasion, the US military established a sprawling base in the remains of the ancient city of Babylon, just north of Hilla, which had been extensively renovated under Saddam Hussein's regime.

According to UNESCO, their presence resulted in serious damage to Babylon's priceless antiquities.

The transfer came two days after a ferocious firefight in the town of Jurf al-Sakhr on the border between Babil and the neighbouring mainly Sunni province of Anbar.

At least 15 people were killed when suspected insurgents clashed with members of Sunni tribes who had formed anti-Qaeda militias to oust the jihadists from their areas.

In Baghdad, a suicide bomber rammed his car into the convoy of Shiite Labour Minister Mahmud Jawad al-Radi, killing 11 people although the minister esaped unhurt, ministry spokesman Abdullah al-Lami told AFP.

Three of his guards were among those killed.

Radi is the second minister from Prime Minister Nuri al-Maliki's 40-member cabinet to have been attacked in less than four months.

In July, Electricity Minister Karim Wahid escaped a roadside bombing in Baghdad which left three of his bodyguards wounded.

AFP