Updated

Iraqi troops took charge of security Wednesday in the southern province of Maysan, a region that borders Iran and the fourth province to come under full Iraqi security control since the 2003 U.S. invasion.

A ceremony was held in the provincial capital of Amarah, 200 miles southeast of Baghdad, and was attended by senior Iraqi and coalition officials including Iraqi National Security Adviser Mowaffak al-Rubaie and the British commander in southern Iraq, Maj. Gen. Jonathan Shaw.

At the handover ceremony, al-Rubaie said in order for a timetable to be set for the withdrawal of foreign troops, Iraqi forces and local authorities have to be ready to take over. He was apparently referring to calls by some Sunni groups and followers of radical Shiite cleric Muqtada al-Sadr to set a timetable for such a pullout.

"We should work to create these circumstances in all provinces, in order to revert security to Iraqis and end the foreign presence," said al-Rubaie, who represented Prime Minister Nouri al-Maliki, the commander-in-chief of Iraq's armed forces.

Al-Maliki was supposed to attend the ceremony but his trip was canceled without explanation.

On Monday, al-Sadr's six ministers quit the Iraqi Cabinet to protest al-Maliki's refusal to back calls for a timetable for U.S. withdrawal.

U.S. Ambassador Ryan Crocker and the commander of U.S. forces in Iraq, Gen. David Petraeus, said in a statement that the handover "demonstrates another step toward a stable and secure Iraq."

"The transition of responsibility in Maysan province represents another step toward Iraqi self-reliance. With the continued support of the Coalition, Iraq will continue to progress along a path to national unity, improved security, and increasing prosperity that benefits all its citizens," the statement said.

Hundreds of British troops are based in Maysan and are not expected to withdraw from the area immediately.

"Multinational forces will continue to train and mentor the Iraqi security forces and patrol Maysan's borders. Our border patrols will assist the government of Iraq in its work and will not impinge upon the duties of the provincial government of Maysan," said Shaw, the British general.

"In the event of a crisis situation in Maysan, God forbid that this should happen, we will retain the capability to intervene — but only at the behest of a democratic government of Iraq," he said.

Maysan is the fourth province to come under Iraqi security control, after the southern provinces of Dhi Qar, Muthanna and Najaf. Al-Rubaie said three Kurdish provinces in northern Iraq would follow next month, and then the southern provinces Karbala and Wassit.

He called on residents of the province to protect it from infiltrators from neighboring countries — an apparent reference to Iran, which borders Maysan to the east. The border crossing point of Sheeb has been closed since February, when Iraqi and British troops blocked the gates with large metal shipping containers.

Another border crossing at Shalamcha in the nearby province of Basra was closed the same day.

"Protect your border with neighboring countries from infiltration. This is your responsibility, you the residents of the province. I hope that the Sheeb border point will be reopened to make it easier for travelers to cross in an official and controlled way," al-Rubaie said.

Last week, U.S. military spokesman Maj. Gen. William Caldwell said that Iran has been training Iraqi fighters in the assembly of deadly roadside bombs known as EFPs, explosively-formed penetrators. In January, U.S. officials said at least 170 U.S. soldiers had been killed by EFPs.

Prime Minister Tony Blair has announced that Britain will withdraw about 1,600 troops from Iraq in the next few months, and plans to make more cuts to Britain's 7,100-strong contingent by late summer.