Bamako - Three European aid workers released in Mali after being kidnapped by an Al-Qaeda-linked group, were freed in exchange for three Islamists, a negotiator said as they headed home.

The Islamist militant group, the Movement for Oneness and Jihad in West Africa (MUJAO), claimed it had received a ransom of 15 million euros ($18.4 million) as well as winning the freedom of one imprisoned fighter.

"We got 15 million euros for the release of the three hostages and we also secured the release of a mujahideen imprisoned by Mauritania" in return for freeing one Italian and two Spanish aid workers on Thursday, Walid Abu Sarhaoui told AFP.

Mauritanian news site ANI said a ransom of two million to three million euros had been paid.

The freed hostages Spaniard Enric Gonyalons, female compatriot Ainhoa Fernandez Rincon and Italian Rossella Urru arrived Thursday at the airport in Burkina Faso's capital Ouagadougou, looking tired but relieved.

The three had arrived on a Burkinabe military plane sent to pick them up in the north Malian city of Gao. Then, accompanied by intelligence officials from their countries, they boarded two planes to go home.