TORONTO - Four al Qaeda members, including a bomb-maker, were released from prison in the African country of Mali in exchange for the freedom of two Canadian diplomats this spring, a newspaper reported Saturday.

The diplomats, Robert Fowler and Louis Guay, were kidnapped in Niger last December and held for more than four months by an al Qaeda offshoot, known al Qaeda in the Islamic Maghreb or AQIM.

In a report from Mali, the Globe and Mail said the prisoner release was confirmed by government sources and by a local intermediary involved in negotiations to free the diplomats.

It also said Ottawa is maintaining that it played no part in the release of the al Qaeda members.

The newspaper said the released prisoners were Mauritanian members of AQIM. It added that one of them, known as Sidi, was a bomb-maker who was involved in an explosion in Mali last year.

Fowler, the United Nations special envoy to Niger, and his aide Guay were taken at gunpoint Dec. 14 while driving on a main road about 40 kilometres northwest of the capital, Niamey.

Fowler was on a mission to mediate between the Niger government and a rebel movement, fighting over resource royalties.

Following the kidnapping, the Niger government appeared unco-operative but denied any involvement. The diplomats were ultimately freed in Mali on April 21.

Fowler was Canada's longest-serving ambassador to the UN, holding the post from 1995 to 2000.

He was ambassador to Italy for six years after that and is considered an expert on Africa.