President Umaru Yar'Adua has promised money and jobs to militants
The last prominent militant in Nigeria's oil-rich Delta region has given up his weapons after agreeing to a government amnesty deal.
Government Tompolo, who heads the main rebel faction in the western Delta, disarmed in return for promises of cash and education for his fighters.
On Saturday, two other commanders from the eastern Delta laid down weapons.
The amnesty is part of government efforts to end years of rebel attacks on the Nigerian oil industry.
Mr Tompolo is considered one of the most important rebels figures in the oil-rich Delta.
Militants there have claimed responsibility for numerous attacks on Nigeria's oil infrastructure, as well as kidnappings for ransom.
The rebel leader accepted President Umaru Yar'Adua's amnesty deal on Saturday, 24 hours before the offer expired.
"Today is the greatest day for Nigeria," he said on Sunday as he arrived in the southern city of Warri, from where he travelled by boat to his Oporoza camp for the disarmament ceremony.
Hundreds of supporters and local people also made the journey to witness the weapons' handover.
Among them was Defence Minister Godwin Abbe, who described Mr Tompolo's surrender of arms as "an act of patriotism" and "a dream come true".
"It's an indication that peace has finally come to the Niger Delta. The time has come for us to settle down as a country and find a solution to the problem that led to the crisis in the region," he said.
Ateke Tom has led many attacks on Nigeria's oil industry
The ceremony comes a day after two prominent militant commanders in the eastern Delta, Ateke Tom and Farah Dagogo, led their supporters in surrendering their weapons.
Mr Dagogo said he was accepting the amnesty "with the hope that it will usher in a true spirit of reconciliation".
Fellow militant leader Mr Tom and hundreds of his followers also disarmed at the beach ceremony in Port Harcourt.
Mr Tom said the government needed to ensure that promises made to fighters were kept.
"We must get what we want. The government are very trickish, we're watching them," he told Reuters.
The militants took up arms in 2006, saying proceeds from the Delta's oil wealth had not benefited local people.
Although Nigeria is the world's eighth-largest oil exporter, the unrest has prevented it from pumping much more than two-thirds of its production capacity.
The 60-day government amnesty came into place in August, offering cash, training and a rehabilitation programme for any fighter who laid down arms.
Hundreds of militants have already taken up the offer and President Yar'Adua's special adviser on the Delta, Timi Alaibe, has said he is confident that all militants will eventually give up the fight.
But the BBC's Caroline Duffield in Lagos says that what the government calls its peace process is murky, and it is unlikely that any of the guerrillas are giving up all their arms.
Questions still remain about the future of the thousands of militants, she adds, and a minority of militants say they will continue to fight, with new leaders replacing those who stepped aside.