YENEGOA, Nigeria (Reuters) - Royal Dutch Shell on Monday began helping retrain former oil militants in Nigeria responsible for years of attacks on its pipelines, part of efforts to ensure an amnesty programme brings lasting peace.

The Anglo-Dutch giant, Nigeria's longest-standing foreign oil partner, is working with the federal government and local authorities in the Niger Delta to try to ensure that gunmen who laid down weapons earlier this year do not return to violence.

The government says thousands of fighters handed over their weapons during an amnesty period which ended just over a month ago, the most serious bid yet to stop unrest which has prevented Nigeria pumping much above two thirds of its oil capacity.

Thousands of guns, grenades and rounds of ammunition may have been surrendered during President Umaru Yar'Adua's two-month amnesty, but analysts say peace will only be sustained if work can be found fast for those who disarmed.

"In co-operation with the government and the states, we are taking on ex-militants to train them in business development, to teach them what real business is all about," Shell's Africa communications director Olav Ljosne told Reuters.

"We of course look at their education and the background of the guys so that we can see that they can make use of it and develop from it," he said.

Years of pipeline bombings, attacks on facilities and the kidnapping of oil workers have prevented Nigeria from pumping much above 2 million barrels per day of oil.

The instability was costing the country $1 billion a month in lost revenue, according to the central bank, and last year helped push world oil prices to record highs near $150 a barrel.