The main militant group in Nigeria's southern oil region, the Movement for the Emancipation of the Niger Delta, said it blew up an oil facility operated by Royal Dutch Shell just hours after President Umaru Yar'Adua declared an amnesty.

The group said that its militants had blown up a well head in the country's main oil producing region in retaliation for an army operation in western Niger Delta. The military has denied raiding a community in the Niger Delta on Thursday

MEND has increased its campaign of sabotage against Nigeria's oil industry since the army launched its biggest offensive against rebels last month.

Since early 2006, militants have kidnapped hundreds of local and foreign workers and attacked oil and gas pipelines and other facilities in the region. They say they are fighting for a greater share of oil revenues for the impoverished people of the region.

MEND's claim came hours after President Umaru Yar'Adua proclaimed an amnesty for the rebels. Mr. Yar'Adua on Thursday offered amnesty to all gunmen in the Niger Delta who lay down their weapons by October 4, in a bid to stem the insecurity which has cost Africa's top oil exporter billions of dollars in lost revenue.

A Niger Delta activist, Ankio Briggs, said the president's offer did not go far enough.

"What the president has said, in a nutshell, is that what they want really is access. Whatever will give them access to the oil and gas is really what they are looking for. It [amnesty] does not really address the very burning issues of the crisis in the Niger Delta; like how it came about that the Niger Delta is so underdeveloped. We find ourselves going round and round in circles, a lot of time is being wasted," said Briggs.

Since the 1970s, Nigeria has pumped more than $300 billion worth of crude from the southern delta states, according to government estimates. But high unemployment in the delta, environmental degradation due to oil and gas extraction, a lack of basic resources such as fresh water and electricity have angered some of the region's youth and incited them to take up arms.

Ankio Briggs said lasting peace in the Niger Delta can only be realized with massive development of the region and a fairer distribution of the oil wealth.

"We expected to see a declaration that took us further than where we are, for the president to say to the nation, the world and to the oil companies how are we going to move from where we are, that is in terms of development, in terms of justice, in terms of zero tolerance for the looting of the peoples resources? There is a lot of injustice in the sharing formula," he said.

The government has announced several crackdowns on the violence, and pledged to address the region's grievances. But the people of the delta say they have seen many promises of development go unfulfilled and the military response does not appear to be working.