Radical Iraqi Shiite cleric Muqtada al-Sadr called on his followers Thursday to end clashes with Shiite rivals so that stalled talks on a new constitution can proceed.

Clashes continued for a second day after the cleric's office in Najaf was burned and four of his supporters killed.

It was just after the appeal by al-Sadr that leaders of the country's political factions met in the Green Zone to try to hammer out an agreement on the draft constitution on the final day of an extension granted Monday night by parliament after Sunni Arabs blocked a vote on the accord accepted by Shiite and Kurdish negotiators.

After meeting 15 Sunni members of the constitution drafting committee, Iraq's President Jalal Talabani said consensus on the new constitution could be reached soon.

``I urge the believers not to attack innocent civilians and not to fall for American plots that aim to divide us,'' al-Sadr said. ``We are passing through a critical period and a political process.''

The crisis erupted Wednesday when al-Sadr's supporters tried to reopen his office across the street from the Imam Ali mosque in Najaf, the most sacred Shiite shrine in Iraq. Rivals tried to stop the move, fights broke out and the office was set afire.

Armed attacks against offices of al-Sadr's movement and the rival Supreme Council for the Islamic Revolution in Iraq then spread across the Shiite heartland of central and southern Iraq.

Before al-Sadr spoke, the violence continued Thursday.

Al-Sadr supporters in Diwaniyah, 170 kilometers south of Baghdad, occupied parts of the city, setting up checkpoints and firing on police and rival groups.

In Baghdad, SCIRI members torched a building belonging to al-Sadr's movement in the Nahrawan suburb. In retaliation, al-Sadr followers set fire to an office of SCIRI's Badr Brigade militia in Baghdad's heavily Shiite neighborhood of Sadr City.

Clashes were also under way in Amarah, where al-Sadr's militiamen attacked the headquarters of the Badr group with mortars.

Five attackers were killed, al-Sadr officials claimed.

And clashes broke out before dawn in Basra, the country's second city, but the city settled down after daybreak.ASSOCIATED PRESS