A sabotage attack on a cluster of about 20 oil pipelines in southern Iraq has cut exports from the key oil producing region by half, a top oil official said Thursday.

It was the latest insurgent attack to set back Iraq's oil sector, a key source of funding for reconstruction.

The pipelines were attacked late Wednesday in Berjasiya, 20 miles southwest of the southern city of Basra, an official with the state-run South Oil Co. (search) said on condition of anonymity.

Oil exports out of southern Iraq average about 1.85 million barrels a day. The oil official said Wednesday's sabotage cut exports to 900,000 barrels. The country's southern pipelines export 90 percent of Iraq's oil.

The pipelines, which connect the Rumeila oilfields to Berjasiya, were ablaze after the attack, but those fires were put out late Thursday, the official said.

The official said it would take at least three days to repair the damage.

Earlier Thursday, Associated Press Television News footage showed huge plumes of black smoke and flames leaping from the Zubayr 1 pumping station, south of Basra. Emergency workers struggled to douse the fires with water hoses.

Squadron leader Spike Wilson, a spokesman for British troops helping maintain security in the area, said he was only aware of one pipeline breach, 12 miles west of Zubayr.

He said it was not clear if that pipeline had been attacked, however.

"It's a minor pipeline, it hasn't impeded the export of oil at all," Wilson said. "Because the infrastructure of the pipelines are so old, they frequently just give way."

Insurgents have repeatedly sabotaged Iraq's crucial oil industry, its main source of income, in an effort to hamper reconstruction efforts here. The threats to the oil infrastructure have increased in recent weeks amid a violent uprising by Shiite militants in southern Iraq, where much of the oil industry is located.

Supporters of radical Shiite cleric Muqtada al-Sadr (search) have threatened to sabotage Iraq's crucial oil infrastructure to protest the ongoing clashes between militants and U.S. and Iraqi forces in the holy city of Najaf (search).

On Aug. 19, Shiite militants stormed the headquarters of Iraq's South Oil Co. and set it on fire.

Interim Prime Minister Ayad Allawi (search) said last week the fighting in Najaf has cost the country $160 million in lost exports. Attacks by saboteurs in July cost the government $1 billion in oil sales over 10 days, Allawi said.

Oil exports are a key source of funding for the government's efforts to rebuild the country after years of war and devastating sanctions.