The Joint Revolutionary Council said its militants in Buguma in the south of Nigeria "attacked and exploded" the Shell pipeline, CNN International reported.
Shell said it couldn't confirm the explosion but it had been informed of the JRC claims.
The Movement for the Emancipation of the Niger Delta, the main militant group in the region, announced a formal end to an October cease-fire in February, saying oil companies should prepare for "an all-out onslaught."
Niger Delta militants complain they are cut out of oil revenue generated in the poverty-stricken area.
Nigeria is a major supplier of oil to the United States, though it holds only 3 percent of the world's oil reserves.
Violence and political instability are costing the oil-rich country dearly in terms of production. Production levels dropped nearly 30 percent in recent years, costing the government billions of dollars in lost oil revenue.
The latest attacks occurred Friday.