LAGOS, Nigeria (CNN) -- Nigeria's main militant group said Friday it destroyed another oil pipeline owned and operated by a foreign company in the Niger Delta region.
File image shows Movement for the Emancipation of the Niger Delta fighters.
It is the third reported attack this week by the Movement for the Emancipation of the Niger Delta, or MEND, which demands a fairer distribution of the country's oil wealth.
"Heavily armed fighters" blew up a "major" crude oil pipeline run by the Italian gas company, Agip, in Bayelsa state early Friday, MEND spokesman Jomo Gbomo said in an e-mail.
There was no immediate word from Agip about the purported attack. Some companies in the region have shut down their operations in the Niger Delta in the wake of ongoing violence there.
The fighters reached the pipeline after overpowering a Nigerian military gunboat, Gbomo said.
"All the soldiers numbering seven (7) were dispossessed of their weapons," he said. "The gunboat was also stripped of its weapons before it was disabled by explosives. The soldiers pleaded for their lives to be spared and we did."
The militant group said it blew up Shell's major crude oil trunk line late Wednesday in Bayelsa state, as part of its campaign "to cripple the entire oil and gas export of the Federal Republic of Nigeria." MEND called on the company to "vacate the Niger Delta region to avoid collateral damage to their investment and death to staff."
Shell confirmed an attack on its pipeline in Bayelsa on Wednesday, saying it shut down some production "to avoid potential environmental impact," spokesman David Williams said.
"There's a joint investigation underway to determine the quantity of crude (oil) spilled," Williams told CNN from the company's headquarters in The Hague, Netherlands.
MEND also claimed to have attacked a Chevron oil station in the Niger Delta region Monday and threatened further attacks in other states in the Niger Delta region, as well as on offshore oil facilities.
At the time, a Chevron spokesman said it was investigating the reported attack on its Abiteye flow station. The U.S.-based company halted its onshore operations in the region last month.
MEND on Monday also warned the international football association FIFA that it should "rethink" allowing Nigeria to host the upcoming under-17 World Cup series later this year.
"The safety of international players and visitors can not be guaranteed due to the current unrest," MEND said in an e-mail.
Only two out of the nine stadiums in Nigeria are close to being ready for the tournament which is scheduled to take place between October 24 and November 15, according to FIFA. The association has given the country a grace period to start constructing the remaining venues, FIFA Vice President Jack Warner said.
Last month, the militant group declared an "all-out war" on the government after what it said was a deadly bombing raid on civilians.
It is not the first declaration of war by MEND, which demands that more of Nigeria's oil wealth be reinvested in the region instead of enriching those whom the militants consider corrupt politicians.
The militant group declared war against the government in September for what it said were unprovoked attacks. At that time, MEND destroyed several oil facilities, forcing Nigeria to cut its oil exports by as many as 1 million barrels of oil per day, or 40 percent.
The recent violence -- which has included attacks on pipelines and hostage-taking -- has limited shipment of crude oil supplies out of Nigeria, Africa's largest producer.