Militants in Nigeria have claimed to have blown up two key oil pipelines in the Niger Delta region.

The pipelines are operated by the Anglo-Dutch oil giant Shell, and the Italian group Agip.

The Movement for the Emancipation of the Niger Delta (MEND) said in a statement it blew up the pipelines in a pre-dawn attack in Bayelsa state as part of a campaign to cripple the nation's main industry.

'The Agip pipeline which connects the Agip Brass terminal was sabotaged at Nembe creek while the Shell Nembe creek line was done at Asawo village, all in Bayelsa state,' the militants said.

It was the seventh in a series of attacks on oil installations in just under two weeks since the Nigerian government extended an amnesty offer aimed at ending a three-and-half-year insurgency.

Unrest in the Niger Delta costs Nigeria hundreds of thousands of barrels a day in lost crude oil production. Militants say they are fighting for a greater share of the oil wealth.

MEND is the strongest of the groups which have been fighting in the region since 2006.

Nigeria's military said yesterday it had arrested three men suspected to be planning an attack near oil facilities in the Delta.

On Monday, MEND said it had destroyed a Chevron oil pipeline junction at Okan and seized six crew from a tanker.

It also claimed at the weekend to have attacked a Shell well-head in Rivers state, and reacted to the announcement of a multinational trans-Saharan gas pipeline, saying it would face 'the same fate other pipelines are facing today.'