The militants in the Niger Delta are heavily armed
An offer of an amnesty for militants in Nigeria's oil-rich Niger Delta region has come into effect.
In the next two months the government hopes about 10,000 rebels will exchange weapons for a pardon and retraining.
But reports suggest few rebels have surrendered on the amnesty's opening day, and it is unclear how many armed groups will take part in the amnesty.
They attack oil refineries and smash pipelines in what they say is a fight for a fair share of the Delta's wealth.
In recent months the violent struggle in the region has worsened, but the amnesty offer is being hailed by analysts as one of the most significant efforts so far to end the unrest.
Timiebi Koripamo-Agary, spokeswoman for the amnesty programme, said the militants had made their point.
"They have raised the issues of the Niger Delta sufficiently to national and international consciousness," she said.
"This amnesty, I believe, offers the militants the opportunity to engage in finding lasting solutions to the problems of the Niger Delta."
She said hundreds of militants had expressed interest in taking the clemency, including one commander who said he and 800 fighters were ready to accept the offer.
Offices have been set up around the region where militants can go to hand in their weapons.
But the BBC's Abdullahi Kaura Abubakar, outside an office in Port Harcourt, says no militants have arrived and no guns have been handed in.
He says it is a similar story at other offices around the region.
More than 10,000 militants hiding out in 50 to 60 camps
More than 250 expatriate oil workers kidnapped since 2006
Rebellion cuts oil production by estimated one million barrels a day
Oil firms spent $3.7bn on security in 2008
Militants and others stole estimated $92bn worth of oil between 2003 and 2008
Sources: Reuters, Legaloil.com
Officials said gunmen who accept amnesty would be given 65,000 naira ($433; £255) a month for food and living expenses during the rehabilitation programme, which runs from 6 August to 4 October.
But the main rebel group in the region, the Movement for the Emancipation of the Niger Delta (Mend), has not yet said it will take part in the amnesty.
"When we choose to disarm, it will be done freely, knowing that the reason for our uprising which is the emancipation of the Niger Delta from neglect and injustice has been achieved," the group said in statement e-mailed to the AFP news agency.
The group, which called a temporary ceasefire last month after one of its leaders was freed from jail, is in talks with senior officials about the terms of any possible amnesty.
Oil revenue is the major source of income for the entire country but the so-called oil war has cut Nigeria's oil output by about a quarter in recent years.
The militants tap into pipelines, siphon off oil and sell it on a huge scale. Some analysts estimate the illicit industry generates more than $50m a day.
The BBC's Caroline Duffield, in Nigeria, says some of the most powerful people in Nigeria directly profit from the militants' activities.
With that kind of money involved, our correspondent says, it is hard to see why the militant gangs or their powerful patrons would want peace at all.