Boko Haram is holding a French priest who was kidnapped in northern Cameroon, a source in the banned Nigerian Islamist group has said.
Georges Vandenbeusch was on Wednesday snatched from his home near the town of Koza in northern Cameroon, about 30km from the Nigerian border.
"I can confirm that the French priest is in the hands of mujahideen (fighters) from Jamaat Ahl al-Sunna Li Da'wat al-Jihad, who carried out the operation that was co-ordinated with Ansaru," the source told the AFP news agency on Friday.
The kidnapping came days after both Boko Haram and Ansari, a splinter group, were designated by the United States as "foreign terrorist organisations".
Ansaru has previously claimed kidnappings of foreign nationals and both groups are blamed for widespread violence in northeast and central Nigeria that has left thousands dead.
Vandenbeusch was seized by about 15 people, who burst into his Nguetchewe parish base, according to the bishop of the Nanterre diocese near Paris, which has authority over the cleric.
The Boko Haram source, who did not want to be identified, declined also to say where the 42-year-old priest was being held, after the Cameroon authorities said they feared he had been taken across the border into Nigeria.
Speaking in Paris after talks with Togo's President Faure Gnassingbe, French President Francois Hollande said Vandenbeusch had "most likely" been taken to Nigeria.
"We are checking all the information that we can get," he told reporters, adding that he would speak with his counterpart in Cameroon, Paul Biya, and vowing that France was doing "all it could to find... and free" the priest.
"The fight against terrorism is still our main concern and common purpose," he added.
Vatican spokesman Federico Lombardi described the kidnapping as "an extremely serious and horrible case, reflected the spread of hatred and violence in the region".
The Boko Haram source promised to reveal more details about the kidnapping "at the appropriate time".