"This has been sustained for some time now, but when the pipelines were being attacked it went down to 1.5m bpd," Maikanti Baru, who heads the Nigerian National Petroleum Corporation, told journalists after a meeting with President Muhammadu Buhari.

The OPEC member's oil production was cut last year by a series of attacks on the infrastructure in the southern Niger Delta region by militant groups.

Nigeria's output was around 1.5 million bpd in April, according to a Reuters survey.

Forcados, a major export pipeline carrying nearly 250,000 bpd in the restive region, is closed. It has only been open for three weeks in the past year, due to militant attacks, with no sign of the pipeline resuming operation.

There have not been militant attacks on pipelines in the last few months and the government has been holding talks with groups, who want a greater share of Nigeria's oil wealth to go to the impoverished region, to broker a peace agreement.