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.
Urru arrived back in Rome late Thursday where she was met at a military airport by family members and Prime Minister Mario Monti.
She said she was well and thanked those who had worked to secure her freedom.
"I was treated well, even if I was frightened several times," she said on arrival, adding that she hoped to return to resume her work in Africa.
A member of the Burkinabe negotiation team, speaking earlier to reporters, said: "There was a compensation, there were releases for releases."
"We do not know if any ransoms were paid... that is between them (the kidnappers) and the countries concerned," he added.
The negotiator said there had been an agreement to free two prisoners held by Mauritania and one held in Niger, but Niger denied being party to a deal.
He also said Gonyalons had been shot in the leg by his captors. "The man is wounded, there was a mujahideen who fired at him deliberately. He is limping a little but it is OK," he said.
Urru told reporters before boarding the flight home: "Thank you very much to Burkina Faso for freeing us."
The previously unknown MUJAO -- a self-proclaimed offshoot of Al-Qaeda in the Islamic Maghreb (AQIM) -- claimed responsibility for kidnapping the aid workers in October 2011 and on Wednesday announced their release.
The hostages were abducted from a Sahrawi refugee camp in Tindouf, Algeria, housing people from the disputed Western Saharan territory that abuts Morocco, Mauritania and Algeria.
In May MUJAO had demanded the release of two Sahrawis arrested by Mauritania for their role in the kidnapping, as well as 30 million euros, threatening to kill the Spanish man if their demands were not met.
The region's Algerian-backed separatist guerrillas, the Polisario Front, said Thursday they were "overjoyed" the hostages had been released and that the group had worked towards getting them freed.
In Nouakchott, online news agency Alakhbar reported that among Islamist prisoners exchanged for the hostages was a Sahrawi called Memine Ould Oufkir, one of those arrested in the wake of the kidnapping.
MUJAO said last week it had freed three of seven Algerian diplomats kidnapped during the seizure of the north Malian city of Gao in late March.
The group, along with the Islamist Ansar Dine (Defenders of Faith) and Tuareg separatist rebels, overran northern Mali in the chaos that followed a March 22 coup in the southern capital, Bamako.
But the jihadists have since forced the Tuareg fighters, who wanted an independent secular state, out of key positions as they seek to implement strict Islamic law.
MUJAO holds Gao, while Ansar Dine has exerted its control in Timbuktu, whipping unmarried couples, smokers and drinkers and destroying ancient World Heritage shrines it considers idolatrous.
Both Islamist groups have stated ties to AQIM and other jihadist groups on the continent, raising fears that the vast region could become a safe haven for extremist groups.
AQIM has for years carried out attacks, kidnapped foreigners and been involved in drug and human trafficking in the Sahel.
The group currently holds six French hostages -- two geologists kidnapped last November in northern Mali and four seized in September 2010 from Niger.
There are also Swedish, Dutch and South African hostages taken last November in an attack on Timbuktu in which a German was killed.