The president of Niger acknowledged Tuesday that a Canadian diplomat who disappeared during a United Nations mission to the West African nation last month was kidnapped by rebels.

"All of our investigations lead us to believe that he was taken hostage by this terrorist group and their accomplices," President Mamadou Tandja told diplomats at a ceremony in the capital of Niamey.

His statement marked the first time authorities in Niger have publicly commented on the disappearance of Robert Fowler, the UN's special envoy to Niger, who went missing along with his assistant and a driver on Dec. 14. Their car was found abandoned about 50 kilometres northeast of Niamey.

The Front For Forces of Redress, a Tuareg rebel group, claimed responsibility for Fowler's kidnapping in a statement posted on its website. But the group retracted the claim a few days later, claiming its site had been sabotaged.

"I have one thought that I would like to send out to the special envoy of the UN secretary general and his colleague ... that they quickly regain their freedom," Tandja said.

The United Nations has said that it's working with the governments of Canada and Niger, as well as others in west Africa, to help secure Fowler's release.

The Front is a splinter group of a larger rebellion being fought by ethnic Tuareg nomads in Niger's northern desert. The Tuaregs, a nomadic people living in the vast sand dunes of the Sahara Desert, have long been at odds with the government of Niger.

A rebellion broke out in 1990 and ended with a 1995 peace accord. But hostilities resumed last year as the government began actively drilling for uranium in the northern desert.