By Tife Owolabi and Alexis Akwagyiram

YENAGOA, Nigeria (Reuters) - Militants in Nigeria's southern Niger Delta oil hub attacked a pipeline operated by the Nigerian National Petroleum Corporation (NNPC), the state oil company said on Wednesday, a day after regional leaders put a series of demands to the president.

Community leaders from the Niger Delta, which is the source of most of the OPEC member's oil, met President Muhammadu Buhari on Tuesday and asked him to pull the army out of the oil hub, order oil firms to move headquarters there and spend more on development to end militancy in the region.

It was the first time that Buhari had met leaders from the since militants started a wave of attacks on oil pipelines in January to push for the impoverished region to receive a greater share of oil revenues.

The military said on Wednesday that troops taking part in a routine patrol in Delta State heard an explosive sound, believed to have been caused by attackers, at Batan Flow Station around Ekweregbene. Sheriff Mulade, a witness, said the attack happened at around 1200 GMT.

NNPC spokesman Garba Deen Muhammad later confirmed that the attack took place. "Production is affected but I cannot tell you by what magnitude," he said.

The flow station is located in a creek between the southern city of Warri and the Forcados oil terminal, which last week resumed crude exports following repairs after an attack.

Although attacks had cut oil production by around a third in recent months, the oil minister said on Tuesday production was back up to 2.1 million barrels a day.

The production rise follows a ceasefire observed by many militant groups in the region over the last few months.

Niger Delta Avengers, the most active group in the region, said in August it would halt hostilities. Since then it has carried out two attacks - one in September and another last week.

Nigeria has held months of talks to end the violence but no lasting ceasefire has been agreed in the oil hub, where many complain about poverty, even though the region provides much of Nigeria's oil exports.

Any ceasefire would be difficult to enforce as the militants are splintered into small groups of angry, young unemployed men whom even their leaders struggle to control.

(Editing by Alison Williams)