LAGOS, August 25, 2008 (AFP) - The most prominent armed group in Nigeria's volatile oil-rich Niger Delta, MEND, on Monday accused the military of killing 12 people after attacking their boat.

'A civilian commercial transport boat which plies the Yenagoa-Fropa (southern Ijaw) route of Bayelsa state was attacked by the men of the military Joint Task Force (JTF) on Sunday, August 24, 2008, by about 16:30 hours,' MEND said in an email to AFP.

'The JTF's explanation of the attack which led to the death of 12 passengers and one critically injured survivor made up of students, women and children, was that they heard the sound of gunfire minutes before the emergence of the passenger boat,' the Movement for the Emancipation of Niger Delta said.

The group called for the withdrawal of soldiers from the restive region.

'This unfortunate killing of innocent civilians again calls for the replacement of the military task force with the police in civilian areas,' it said urging the Bayelsa state government to investigate the incident and compensate the families of the victims as soon as possible.

MEND which says it is fighting for greater control of the region's oil wealth by local people, came into prominence in January 2006.

It has carried out a series of violent attacks on the oil industry and kidnapped hundreds of local and expatriate workers in the Niger Delta.

Several foreign firms have left the Niger Delta because of the security problems.

The unrest has reduced Nigeria's oil output by a quarter, causing it to lose its position as Africa's biggest oil producer to Angola, according to April figures from the Organization of the Petroleum Exporting Countries.