OUAGADOUGOU - Three European aid workers released in Mali after being kidnapped by an Al-Qaeda-linked jihadist group were freed in exchange for three Islamists, a negotiator said on Thursday.

"There was a compensation, there were releases for releases," a member of the negotiation team told reporters, adding that the three hostages had boarded planes home after arriving in Burkina Faso earlier in the day.

The three -- a Spanish man and woman, Enric Gonyalons and Ainhoa Fernandez Rincon, and an Italian woman, Rossella Urru -- were described as "well" although Gonyalons had been deliberately shot and wounded by one of his captors during his captivity.

"The (Spanish) man is wounded, there was a mujahideen (fighter) who fired at him deliberately, he is limping a little but it is OK," he said.

The previously unknown Movement for Oneness and Jihad in West Africa (MUJAO) claimed responsibility for the aid workers' kidnap in October 2011, saying it was an offshoot of Al-Qaeda in the Islamic Maghreb (AQIM).

The group on Wednesday announced their release and said a ransom had been paid.

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 ($37 million) for the hostages' freedom, threatening to kill the Spanish man if their demands were not met.

"We do not know if any ransoms were paid... that is between them (the kidnappers) and the countries concerned," the negotiator added.

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 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 Islamist seizure of the northern Mali 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 of Bamako.

However 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 the city of 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 is currently holding six French hostages -- two geologists kidnapped last November in northern Mali and four kidnapped 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.