KANO, Nigeria (AFP) - The banned Nigerian Islamist group Boko Haram on Wednesday said it had released a French Roman Catholic priest on compassionate grounds but insisted that no ransom had been paid.

The militants, considered a terrorist organisation by the United States, claimed responsibility for kidnapping Mr Georges Vandenbeusch, who was seized from his parish in northern Cameroon on Nov 13.

A source within the group said they had demanded a ransom from France through the Cameroon government to release the 42-year-old, who was freed on Tuesday and arrived back in France on Wednesday.

But the French government had refused and requested that Mr Vandenbeusch be released on humanitarian grounds because of his status as a clergyman, the source added.

"The leadership (of Boko Haram) decided to release the priest on compassionate grounds and having benefited from his medical expertise," the source told AFP.

"The priest offered medical service to sick members during his period of captivity. The leadership felt there was no longer need for keeping him." Cameroon has claimed that the cleric was taken across the border into neighbouring Nigeria but it remained unclear where exactly he had been held.

Boko Haram did not disclose where he had been held while Nigeria's military, which is fighting the militants in northeast states bordering Cameroon, also denied knowledge of his presence.