Militants attacked a Chevron platform in Nigeria's oil-rich Niger Delta region late on Wednesday, the U.S. energy company said on Thursday, amid growing fears of a revived militant campaign in the region.

It is the latest in a series of attacks on oil facilities in Africa's top oil exporter. President Muhammadu Buhari has vowed to crack down on "vandals and saboteurs" in the Delta region, which produces most of the country's oil.

In a statement, the energy company said Chevron Nigeria Limited, operator of a joint venture with the Nigerian National Petroleum Corporation (NNPC), said an attack took place at about 11.15 p.m. (2215 GMT) on Wednesday.