Major Ali Mahmud said National Guard forces were trying to extinguish a fire which damaged 150 metres of the Khana pipeline, northeast of Baghdad.
He said another bomb was found on Saturday along the same line, and was safely defused.
An oil official said saboteurs on Friday blew up a section of another oil pipeline in Mashada area, about 50km north of Baghdad. The pipeline feeds the same refinery which processes 110,000 barrels per day (bpd).
Attacks by armed fighters on Iraq's oil pipelines have disrupted refinery operations, and cost the US-backed interim government billions of dollars, including lost oil export proceeds and nearly $200 million a month worth of refined product imports.
Saboteurs also hit a section of the northern oil export network on Thursday. Oil officials said crude kept flowing normally through alternative pipelines to Turkey's Ceyhan port at 300,000 bpd.
Iraq exports another 1.6 million bpd through two southern offshore terminals in the Gulf, and the flows there have been normal for about two months, the officials said.