Robin Hughes, among 27 oil workers kidnapped by militants when their vessel was hijacked over six months ago, has been handed over to military officials in Nigeria's southern oil region, an official said.
The official said he had no information on Hughes' condition or if a ransom had been paid to secure his release.
There was no mention of a second British hostage, Matthew Maguire, who is still believed to be in captivity.
Earlier The Movement for the Emancipation of the Niger Delta (MEND) said in an e-mail that Hughes would be freed very soon.
Most of the other hostages kidnapped alongside Hughes were released soon after their capture.
In January MEND released what they said were recent pictures of the two Britons.
They looked dishevelled but not injured and were standing in what appeared to be a forested area.
MEND said they would not be released until the Nigerian government freed its leader, Henry Okah, who is being tried on charges of arms trafficking.
Hundreds of foreigners have been seized in the region since MEND launched a campaign in 2006 to obtain a fairer share of the profits from crude oil extraction.
The southern Niger Delta is home to Africa's biggest oil and gas industry.