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Rebel Shiite cleric Muqtada al-Sadr (search) called for his followers across Iraq to end fighting against U.S. and Iraqi forces and is planning to join the political process in the coming days, an al-Sadr aide said Monday.

Meanwhile, Iraqi oil exports came to a halt after a rash of insurgent attacks on the country's petroleum infrastructure, the cocontracts for light crude were up 26 cents at $43.44 a barrel. But that was well below peaks of over $48 a barrel in mid-August.

The announcement by al-Sadr came as his aides were trying to negotiate an end to fighting in the Baghdad slum of Sadr City and in the southern city of Basra, where clashes have continued even after a peace deal was reached in Najaf, the holy city where al-Sadr militiamen battled U.S. and Iraqi forces for three weeks.

Al-Sadr also called for U.S. and Iraqi forces to withdraw from the center of Iraqi cities, Sheik Ali Smeisim told The Associated Press. However, that did not appear to be a condition for the unilateral ceasefire.

"I call on the interim Iraqi government to have patience ... and to pull back the American and Iraqi forces from the center of Iraqi cities," Smeisim said, speaking on behalf of al-Sadr. "At the same time I call on the forces of the Mahdi Army (militia) to ... stop firing until the announcement of the political program adopted by the Sadrist movement."

When asked if the cease fire would take effect immediately, he said: "I hope so."

The announcement could provide a major boost to the government of interim Prime Minister Ayad Allawi (search). Al-Sadr has fiercely opposed the continued U.S. presence in Iraq and has denounced Allawi's government as dependent on the Americans — but if he decides to join politics, it would suggest al-Sadr's acceptance of the U.S.-backed political process due to lead to elections in January.

Allawi has also demanded al-Sadr disband his Mahdi Army (search) militia, but the aides did not say the cleric was considering doing so. The militia has emerged intact from the weeks of fighting with U.S. forces, and al-Sadr has gained popularity among some sectors of Shiites, particularly the poor.

"This latest initiative shows that we want stability and security in this country by ending all confrontation in all parts of Iraq," said Sheik Raed al-Khadami, al-Sadr's spokesman in Baghdad. "Al-Sadr's office in Najaf will call within the next two days to join the political process."

Al-Sadr visited the Imam Ali Shrine in the city of Najaf for the first time since his militia left the holy site of Friday after weeks of using as a stronghold and refuge during the fighting with the Americamns.

Al-Sadr asked religious authorities for permission to enter the shrine and made a brief visit on Monday, according to the office of Grand Ayatollah Ali al-Sistani (search), Iraq's top Shiite cleric.

Uprisings by al-Sadr's fighters this month and in April increased the security problems faced by Allawi's government, on top of the Sunni Muslim-led insurgency that has plagued Iraq since the fall of Saddam Hussein more than a year ago.

Opposition fighters have been attacking oil pipelines in both the north and the south of the country for months. Late Sunday, oil ceased flowing from southern pipelines — which account for 90 percent of Iraq's exports.

Two senior officials of the South Oil Co. (search), speaking Monday on condition of anonymity, said the lines were not likely to resume operations for at least a week.

Iraq's other export avenue, a northern pipeline to the Turkish Mediterranean port of Ceyhan, also carried no oil Monday, according to an oil official in Ceyhan.

Allawi condemned the pipeline attacks, saying they were making ordinary Iraqis suffer.

"This is causing a great loss for the Iraqi people in terms of revenues, which could be used in the reconstruction of the country and to pay the people and get the economy back on track again," Allawi said in a televised interview Monday.

A halt in southern oil exports costs Iraq about $60 million a day in lost income at current global crude prices, said Walid Khadduri, an oil expert who is chief editor of the Cyprus-based Middle East Economic Survey.

The latest strikes, which hit five pipelines linked to the southern Rumeila oil fields on Sunday, immediately shut down the Zubayr 1 pumping station, forcing officials to use reserves from storage tanks to keep exports flowing for several hours. The reserves ran out late Sunday, the South Oil Co. official said.

Before the attack, Iraq's exports from the south were about 600,000 barrels a day — a third the normal average of 1.8 million barrels a day due to a separate string of attacks early last week. The pipelines were still ablaze Monday, the official said.

Saboteurs last brought southern oil exports to a halt in June.

The job of guarding oil pipelines primarily falls to the U.S.-trained Iraqi infrastructure protection service, although some U.S. soldiers continue to be to be involved. But the military has repeatedly said protection is difficult since oil facilities are so spread out, and the entire network of pipelines can't be constantly watched.

In Baghdad, insurgents fired three mortar rounds into an eastern neighborhood early Monday but there were no immediate reports of casualties, Interior Ministry spokesman Col. Adnan Abdul-Rahman.

South of the capital, gunmen fired on the motorcade of the government's top official in charge of Shiite religious affairs, Sheik Hassan Baraka al-Shami, wounding two of his bodyguards, his spokesman said Monday.