The authorities in Nigeria say as many as 15,000 oil militants active in the Niger Delta surrendered under the two-month amnesty which expired on Sunday.
The official in charge of the scheme said 5,000 weapons and 18 gunboats had also been handed in by the militants.
President Umaru Yar’Adua is to meet some of the militant commanders who have surrendered in Abuja on Friday.
However, one militant faction says it will resume fighting and that most of those who had disarmed were “rented”.
Attacks on oil installations and their employees have cut Nigeria’s output by a third in the past three years and helped raise oil prices.
Mr Yar’Adua has made bringing peace to the delta a priority.
‘Empty’ threat
Speaking at a news conference in the capital on Thursday, chief amnesty co-ordinator Air Vice Marshal Lucky Ararile said 8,299 militants had officially been disarmed since August, but that he expected the figure to rise considerably because there had been a last-minute rush before the programme ended.
“Eventually, we will be looking at about 14,000 to 15,000 by the time the men are fully documented,” he said.
AVM Ararile said the government had so far built only three centres to educate and house the thousands of former militants in the Niger Delta, and would have to build more if it did not want them to have to wait too long.
“We will have a total capacity for 2,400 people at a time, but we are talking about 15,000 ex-militants,” he said.
“The constraint here is the amount of bed space that is available. Re-orientation training will take a month, so we will take in 2,400 per month,” he added.
Some ex-militants in the delta have also reportedly taken to the streets in protest at the government’s failure to pay them the promised monthly living allowance of 65,000 naira ($435), and threatened to take up arms again.
Earlier, one faction of the Movement for the Emancipation of Niger Delta (Mend) led by Henry Okah said most of those who had surrendered “were rented by the government in the hope that real militants would be persuaded to emerge”.
The group said its commanders had been replaced and that it would resume attacks on oil pipelines and installations from next Thursday.
“We will fight for our land with the last drop of our blood regardless of how many people the government of Nigeria and the oil companies are successful in bribing,” said an e-mail sent by Mend spokesman Jomo Gbomo.
Mend declared a 60-day ceasefire on 15 July to allow for peace talks shortly after Mr Okah was freed from prison. It extended the ceasefire by a month in mid-September despite not having held any formal discussions with the government.
The BBC’s Abdullahi Kaura Abubakar in the Niger Delta says some former leaders of the group have dismissed the threat to resume hostilities as empty, and it is not clear how many fighters belong to Mr Okah’s faction.
AVM Ararile told the BBC: “In any organisation you have renegades. If they want to continue with their activities, that’s their choice.”
Mend says it is fighting so that Niger Delta residents benefit more from their region’s oil wealth. But much of the violence is carried out by criminal gangs.