BBC reported Saturday that Matthew Maguire, 35, was freed and is well. He was among 27 hostages taken from a boat near Port Harcourt last September, and the last one released.
He was held by the Movement for the Emancipation of the Niger Delta. The rebel group said in an e-mail that Maguire had been released at a secret location before being moved to Port Harcourt.
"This news comes a great relief to all concerned," said British Prime Minister Gordon Brown in a statement, "I am glad that, for Mr. Maguire and his family and friends, this ordeal is over."
Maguire was expected back in the Britain on Sunday or Monday, BBC reported.
The British network said hundreds of foreign oil and construction workers have been kidnapped by militants since 2006.