The Nigerian guerilla movement MEND has carried out another attack on a Shell oil installation.

MEND appears to ignore President Umaru Yar'Adua's offer of amnesty to all rebels who lay down their arms and give up the struggle. The move was intended to prevent further attacks on oil installations in the Niger delta and further abductions of oil workers.

The violence in the region has led to a one-third reduction in output since 2006 for Shell and the other oil companies in Nigeria. MEND (Movement for the Emancipation of the Niger Delta) and several smaller groups are fighting for a more equitable distribution of oil revenues from the Niger delta.

Some of the other groups are reportedly considering accepting the president's offer.