ABUJA A video which appears to show a Briton and his Italian colleague who were kidnapped in May in northern Nigeria is being checked for authenticity by foreign ministries, after the hostages said they were being held by al Qaeda.
The one-minute video shows hostages blindfolded and on their knees, while three armed men stand behind them, their faces hidden by turbans, according to the AFP news agency, which was sent the video in Ivory Coast.
It was not clear when the film was made and it could not be independently verified.
"We can confirm that two people, including a British national, were kidnapped in Nigeria on 12 May," a British Foreign Office statement said. "A video has been released allegedly showing the hostages and officials are urgently checking its authenticity."
The Italian foreign ministry also put a statement on its website saying it was evaluating the video.
Al Qaeda's north African wing, Al Qaeda in the Islamic Maghreb (AQIM), is known to operate in neighboring Niger and has kidnapped foreign workers there but this would be the first such incident in Nigeria.
If the kidnappers are members of AQIM it would be a significant escalation in the security threat in Africa's most populous nation, already the scene of attacks in recent months by the radical Islamist sect Boko Haram.
Security experts and diplomats had believed the two men were seized by local criminals in May and said they were not convinced the abductors were al Qaeda members.
"There were no demands made and it could be local gangs pretending to be al Qaeda but even that would be raising the level from previous kidnappings of this kind in Nigeria," one security expert based in Nigeria said.
A western diplomat told Reuters the abduction was escalated to 'the highest level' by the British and Italian foreign ministries some weeks ago, an indication that they were aware of the seriousness of the kidnappers.
The two men were working for a construction company and were seized from their accommodation in the capital of Kebbi state, near Nigeria's northwestern borders with Niger and Benin.
"We are working to secure the hostages' safe and swift release. We ask those holding the two men to show compassion and release them, enabling them to rejoin their families," the British Foreign Office statement said.
Hundreds of oil workers were kidnapped during years of militant attacks in Nigeria's oil-producing Niger Delta hundreds of kilometers away in the southeast, but such attacks are relatively rare in the north.
Boko Haram, whose name roughly translates into "Western education is sinful," has claimed responsibility for almost daily shootings and attacks with homemade bombs in remote northeast Nigeria in recent months.
The group, which wants sharia (Islamic law) more widely applied across Nigeria, has killed hundreds this year.
Intelligence officials have said in the past there is evidence to suggest some Boko Haram members have trained over the border in Niger but the group has an ill-defined command structure, a variety of people claiming to speak on its behalf, and an unknown number of followers.
(Writing by Joe Brock; Editing by Tim Pearce)