French President Francois Hollande welcomed French priest and former hostage Georges Vandenbeusch home to France just after 6.30 on Wednesday morning lauding his "courage" and "self-sacrifice".

The cleric had been held hostage for seven weeks by Islamic militants in Cameroon.

He was greeted by Hollande on the tarmac of the airport near Paris as he stepped off the plane, smiling and looking relaxed.

Vandenbeusch, who is 42, had been kidnapped on November 13 by heavily armed men who burst into his parish at night in the far north of the central African country and took him to neighbouring Nigeria.

Hollande praised Vandenbeusch but also warned other Frenchmen and women in high-risk areas around the world to take care and avoid putting themselves at risk of being abducted.

"We have to warn those who may be at risk in areas where there is danger," said Hollande.

He said this applied not only to "priests who have a mission to accomplish" but to other French nationals.

Vandenbeusch, who was also greeted by loved ones, said he had not been mistreated by his captors despite being kept in "rustic conditions".

He expressed "great joy" at returning home but said people should remember those who are still being held hostage.

The radical Islamist movement Boko Haram claimed responsibility for holding the French priest soon after he was kidnapped.

Vandenbeusch described his time in captivity as a period of "terrible boredom, sadness and anger" because, he said he was very fond of the parish where he worked in Cameroon.

"I was under a tree for a month and a half," he said, explaining that his two main guards spoke a local language and that he did not have anything to read, or a radio.

French Foreign Minister Laurent Fabius, who went to collect the priest in Cameroon, hailed his release as "the best end of year gift".

While the circumstances of the priest's release are unclear, Fabius insisted that France, often accused of paying ransoms for hostages despite stiff government denials, had not paid for the release of the priest.

"The French government does not pay ransoms. There were discussions," Fabius told journalists.

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.

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 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 the French news agency 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."

In his former parish of Sceaux, near Paris, bells rang on Tuesday to celebrate his release.

In a statement, his family thanked French, Cameroonian and Nigerian authorities and all those who supported them during the ordeal.

"At this time of joy, we do not forget the other French hostages, and are thinking of their families," they said.

There are still six French people being held hostage in Mali and Syria, and Hollande also reiterated his support for their families.