A message from an e-mail address known to be used by militants said at least 10 foreign hostages would be released to authorities in two restive southern Nigerian oil-producing states.
The governor of one of the states, Bayelsa, was en route to receive a group of foreign hostages, said Ebimo Amungo, the state's spokesman. He had no details on how many hostages were being released, their nationalities or conditions. Officials from the other state, Rivers, weren't immediately available for comment.
The militants, who are believed to be generally allied with the main Movement of the Emancipation of the Niger Delta, said the released hostages were to include four Britons, three Americans, a Filipino, a South African and at least one Indian.
The British embassy couldn't immediately confirm any release and the U.S. Embassy wasn't immediately available for comment.
Over 200 foreigners, mostly oil workers, have been kidnapped in a year and a half of rising violence in the region where Africa's biggest oil producer pumps its crude.
Both criminal gangs and militants pressing for more state oil revenues for their impoverished areas take hostages, who are generally released unharmed after a ransom is paid. Over two dozen hostages are known to be in captivity across Nigeria's south.
The militants said they were releasing the hostages on "humanitarian grounds," while indicating they would continue attacks despite conciliatory words from new President Umaru Yar'Adua.
Yar'Adua said in his inaugural address last month that he considered the crisis in the Niger Delta one of the stiffest facing his unruly nation of 140 million people.
The main militant group, Movement for the Emancipation for the Niger Delta, said it would halt attacks for one month to give Yar'Adua time to come up with a plan for a final solution to the region's problems. That militant group said it wasn't involved in any release Monday.
The militants making the statement are thought to be an ethnic Ijaw group that claims affiliation with MEND, an umbrella for criminal and militant bands operating in the vast region of swamps and creeks.