A spokesman for Nigeria's state oil company said Wednesday that militant attacks are now cutting the country's daily oil production by about 1 million barrels a day, 40 percent of what the country produced before the militant campaign began three years ago.

Nigeria was producing 2.5 million barrels of oil a day before militants started a campaign of attacks in 2005 that cut the output to 2.1 million barrels a day.

But militants have dramatically stepped up their attacks since Saturday, and Nigerian National Petroleum Corp. spokesman Livi Ajuonuma told The Associated Press that has cut production by more than 1 million per day. That's a further 600,000 barrels a day lost, putting the country's daily output at around 1.5 million barrels produced per day.

"It's a heavy loss," Ajuonuma said. In a fifth straight day of violence, Nigeria's main militant group said Wednesday that it had destroyed an oil-pumping station and a pipeline crossing southern Nigeria in a rare daylight attack.

The Movement for the Emancipation of the Niger Delta said in an e-mail that it had destroyed the pipeline. If confirmed, it would be the group's second attack in a 24-hour period.

The group earlier said it attacked an oil-pumping station overnight, destroying the flow station run by the local unit of Royal Dutch Shell PLC after battling security forces protecting the site. Military spokesman Lt. Col. Sagir Musa confirmed the incident, saying that eight boatloads of militants attacked the facility with bombs, dynamite and hand grenades. Shell officials had no immediate comment.