Shell is temporarily closing the terminal exporting Nigeria's benchmark Bonny Light crude oil as militant attacks have cut production in Africa's biggest petroleum producer.

Shell refused to confirm labor union reports that the company is also evacuating workers from Bonga oilfield following a threat.

A bomb attack last week closed a major Chevron facility. Shell's Forcados export terminal has been shut since an undersea pipeline attack in February.

In a statement Wednesday, Shell declared force majeure on Bonny exports effective 1100 GMT the day before to protect the company from contractual obligations, citing a leak on the Nembe pipeline. Pipeline operator Aieto Exploration blamed sabotage or an attack.

Militants want a bigger share of Nigeria's oil wealth.

Nigeria's production is down to 1.7 million barrels a day from 2.2 million.