BAGHDAD, Iraq - Oil exports from southern Iraq have been brought to a complete halt, a senior oil official said today, following a spate of pipeline attacks launched by insurgents trying to undermine the nation's interim government.

Also today, firebrand Shiite cleric Muqtada al-Sadr visited the Imam Ali Shrine in the city of Najaf for the first time since his militia left the holy site on Friday under a peace deal to end three weeks of fighting with U.S. forces.

Al-Sadr had asked religious authorities for permission to enter the shrine, where his Mahdi Army militia had holed up during the violence in Najaf, and he briefly went in today, according to the office of Grand Ayatollah Ali al-Sistani, Iraq's top Shiite cleric.

Oil flows out of the southern pipelines - which account for 90 percent of Iraq's exports - ceased late Sunday and were not likely to resume for at least a week, two senior officials from South Oil Co. said on condition of anonymity.

"Oil exports from the port of Basra have completely stopped since last night," one official said.

No oil was being pumped today through Iraq's northern export lines to the Turkish port of Ceyhan as well, according to an oil official in Ceyhan. Those lines have also been repeatedly attacked in recent months.

Interim Prime Minister Ayad 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 an interview with CNN aired 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.

Insurgents have launched repeated attacks on Iraq's oil infrastructure in a bid to undermine the interim government and reconstruction efforts.

The latest strikes against five pipelines linked to the southern Rumeila oil fields 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 Sunday's 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 today, the official said.