President François Hollande said on Thursday that Islamist groups holding French hostages in Africa were not trustworthy and should not be taken seriously after Al-Qaeda accused Paris of blocking negotiations for their release.

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• Two French nationals kidnapped in Mali (25 Nov 11)

There are a total of nine French hostages on the continent. On Tuesday the Al-Qaeda in Islamic Maghreb (AQIM) said France was snubbing talks proposed by the group to free four French citizens abducted in Niger in September 2010.

"The less one speaks, the better one can work," Hollande told journalists during a visit to Rungis, a giant wholesale food market just outside Paris.

"There have been contacts," with the kidnappers, Hollande said, adding: "But today, the word of the kidnappers is not credible.

"The best way to get our nationals out of the hands of the people who captured them is to remain as discreet as possible and not to enter into any kind of debate.

"Protecting our citizens, fighting terrorism, assuring the liberation of hostages, all this is not contradictory ... I say to the kidnappers – it is high time that you release them."

The latest kidnap occurred in northern Nigeria last week and it was claimed by the radical Islamist group Ansaru which cited France's push for military intervention in Mali as a justification.

Paris has backed plans to deploy a west African force to northern Mali to flush out Al-Qaeda-linked Islamist groups who took control of the vast desert territory earlier this year after a coup.

Eight French hostages are being held in sub-Saharan Africa and one in Somalia.

In a video released Tuesday by Mauritanian online news agency Sahara Medias, AQIM said France was dragging its feet over the fate of the hostages abducted in 2010.

"France bears responsibility for the halt in negotiations and their complete blockage," said AQIM leader Abou Zeid. "We are for negotiations and we have told France this a year ago."

Hollande said there would be a fresh meeting in Paris on Friday to review the fate of the French nationals in captivity.