Radical Shia cleric Moqtada al-Sadr has ordered heads of his Mehdi Army militia to leave Iraq and asked the government to arrest "outlaws" under a US- backed crackdown, Iraq's president said.
President Jalal Talabani made the remarks after Iraq closed its borders with Iran and Syria and as US and Iraqi troops tightened their grip on Baghdad, patrolling neighbourhoods and setting up checkpoints that searched even official convoys.
Mr Talabani said he was unaware of Sadr's whereabouts. The US military has said the anti-American cleric is in Iran, but his aides insist he is in Iraq's holy Shia city of Najaf. An Iraqi government official said he was in Tehran - but only for a short visit.
"I think many of his top Mehdi Army officials have been ordered to leave Iraq to make the mission of the security forces easier," the president was quoted as saying in a statement from his office.
Washington calls the Mehdi militia the greatest threat to Iraq's security. US and Iraqi forces have arrested hundreds of Mehdi Army members in recent months.
Arab television stations today reported that the leader of al-Qaeda in Iraq, Abu Ayyub al-Masri, had been wounded in a clash north of Baghdad.
Masri, an Egyptian, assumed the leadership of al-Qaeda in Iraq after Jordanian Abu Musab al-Zarqawi was killed in a US air strike in June. The United States has a $5 million bounty on Masri's head.
Insurgents defied a sweep by US and Iraqi soldiers of Baghdad's volatile southern, mainly Sunni, Doura district, exploding two car bombs that killed four people. A bomb on a bus in the Mehdi Army stronghold of Sadr City killed three.