By Mathieu Bonkoungou

OUAGADOUGOU (Reuters) - One Italian and two Spanish hostages freed by their al Qaeda-linked captors in Mali headed home to Europe on Thursday after an accord which mediators said involved a prisoner swap.

The three were earlier flown to a military base in the Burkina Faso capital Ouagadougou. The Burkina officer who headed the operation said two Islamists in jail in Mauritania had been released as part of a deal with Mali's MUJWA, the al Qaeda splinter group which had been holding the hostages.

The three aid workers, kidnapped in Algeria last October, were dressed all in white as they got out of a military plane after it arrived at the base in Ouagadougou.

"We would like to thank the work of Burkina people and the interest for us," Spaniard Enric Gonyalons told reporters.

Ainhoa Fernandez and Rossella Urru, an Italian national, smiled for photographers but gave no statement. The three left soon afterwards on planes heading for Italy and Spain.

"It was a release in exchange for a release," said General Gilbert Diendere, the officer who led the mission, adding that one of two Islamists freed in Mauritania had already been transferred to Mali.

He did not name the Islamists but Mauritanian media and an Islamist prisoner there said on Wednesday that Mamne Ould Oufkir, a suspect in the original kidnapping, had been freed.

The north of Mali is in the hands of local Islamist groups who first fought alongside and then outflanked Tuareg-led separatist rebels who routed government forces there in early April. Continued...