A gas pipeline operated by Nigeria's state energy company in southwestern Ogun state has been attacked by men disguised as maintenance staff, local police said on Thursday.
Attacks by militants on oil and gas facilities in the Niger Delta region - in the south and southeast - over the last few months briefly pushed crude production in the OPEC member to 30-year lows in the spring.
But facilities in the southwest region, which is not part of the Delta area, have so far not been targeted. Militant groups have called for a greater share of Nigeria's oil and gas wealth to go to the Delta, which is the country's main energy hub.
Muyiwa Adejobi, a spokesman for Ogun state police said the attack took place on Tuesday night in the town of Ogijo.
"We were told that some guys came in two vehicles dressed as officials in charge of repairs and maintenance of the gas pipelines and then used dynamite to blow up the gas line belonging to a subsidiary of (state energy firm) NNPC," he said.
"Unfortunately one of the lines was damaged. There are other lines that were not affected," he added.
The pipeline supplies the commercial capital Lagos, which is around 80km (50 miles) from Ogun state, and other parts of the southwest.
Adejobi said there were "insinuations that militants could be responsible" but added that police "are not jumping to conclusions yet as to which group was responsible". Nobody has claimed responsibility for the attack.