Saboteurs drilled holes into a key southern pipeline in Iraq, causing pools of oil to spill on either side of the line, police said Thursday.

The breach in the line occurred in the al-Askari (search) district, 12 miles southwest of Basra (search), said Staff Brig. Gen. Ali al-Mousawi, the head of the Iraqi Border Police.

The pipelines runs to offshore export terminals, but it was not immediately clear if oil exports were affected.

Elsewhere, an explosion damaged a portion of a pipeline running between two northern cities, police said.

The explosion on the northern pipeline, which feeds the Beiji (search) refinery about 125 miles north of Baghdad, forced the shutdown of the line. It was not expected to affect the refinery, which is also fed by other feeder pipelines, said Col. Adnan Abdel-Rahman, a spokesman for the Interior Ministry.

The line was reportedly still on fire.

The damage to the pipelines come a little more than a week after exports were cut in half by damage to the smaller of two key export pipelines.

That line was repaired July 7, after a roughly five-day outage that cut exports from the south to just 960,000 barrels a day. Iraq exports between 1. 7 million to 1.8 million barrels per day of crude from the south.

The two pipelines have been repeatedly targeted by saboteurs over the past few weeks and, in one attack last month, resulted in a halt of exports for almost a week.

Iraq's interim prime minister, Iyad Allawi, has said the attacks over the past few weeks have cost the country about $1 billion in lost revenue.

Insurgents frequently target the country's oil infrastructure in a bid to undermine the new government's reconstruction efforts, which largely hinge on oil revenue.