(Updates with second attack)

KIRKUK, Iraq, Oct 19 (Reuters) - Bombers blew up a section of an internal pipeline carrying crude oil to the Baiji refinery in northern Iraq on Friday, the latest in a spate of attacks on oil or gas pipelines in the past month.

Police said the pipeline connecting Kirkuk's northern oil fields to the refinery was ruptured by a bomb about 50 km (31 miles) southwest of Kirkuk.

A spokesman for Kirkuk's oil company said it would not affect crude oil exports and that there was only minor damage to the pipeline.

Militants also targeted an oil pipeline near Haswa, 50 km (30 miles) south of Baghdad, causing minor damage that was quickly repaired, the Iraqi army said.

The pipeline feeds the Doura oil refinery in Baghdad with crude from Iraq's southern fields.

Brigadier-General Imad al-Silawi, head of the Iraqi Army's 4th Brigade, 8th Division, said soldiers were ambushed when they went to the scene of the blast.

Seven gunmen were killed in ensuing clashes, he said. The patrol was later hit by a roadside bomb that wounded one soldier.

Iraq's oil infrastructure, shattered by years of war, poor maintenance and under-investment, is often attacked by militants seeking to disrupt the flow of oil, the lifeblood of Iraq's economy. Pipelines are difficult to protect and easy targets.

Friday's attack near Kirkuk was the third on pipelines feeding the Baiji refinery since Sept. 18, when Iraq's northern oil export pipeline to Turkey was also damaged in a bomb attack.

Around 20 percent of Iraq's reserves, the third-largest in the world, are in the north.

The crude oil pipeline connecting Kirkuk to the Turkish port of Ceyhan has mostly been inoperable due to sabotage attacks by insurgents in Iraq since the U.S.-led invasion of March 2003.

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