MADRID/OUGADOUGOU (Reuters) – Two Spanish aid workers  held by al Qaeda's North African wing returned to Barcelona after being freed on Monday, ending a kidnapping that lasted nearly nine months.

Al Qaeda in the Islamic Maghreb (AQIM) seized Albert Vilalta and Roque Pascual while they were traveling through Mauritania with a relief aid convoy last November, the latest in a string of abductions claimed by the group.

The two landed at Barcelona's El Prat airport at about 7:30 p.m. EDT, where they were met by family, friends, and colleagues, including Alicia Gamez, who was kidnapped with them and released in March.

"It's a great day for Roque and for me. It's a really important day for us as we have been kidnapped for nine months in tough conditions but now we are free. I am very happy," said Vilalta in comments to the press at the airport.

"They have treated us well - we have lived like they have, we've eaten like they have, we've slept like they have. But it was very hard in the middle of the desert, they are used to it, but we're not," he added.

Earlier the two, who worked for the Barcelona-Accio Solidario aid group, were received by Burkina Faso President Blaise Compaore, a key player in efforts to end earlier kidnapping dramas.

"They are safe and sound after 268 days in the hands of their kidnappers and (after 268 days) of the Spanish government's concern and efforts to obtain their release," Prime Minister Jose Luis Rodriguez Zapatero told a news conference in Madrid earlier on Monday.

AQIM has said Spain is one of its targets because it is an ally of the United States and part of NATO. In an audio statement sent late on Monday to El Pais newspaper AQIM said Spain had met some of its demands for the release of the two workers and that Madrid's stance should serve as a lesson for France's secret services.

Last month, AQIM killed a 78-year-old French hostage, Michel Germaneau, after a raid in the Sahara desert involving French troops failed to free him.

EU Aid Commissioner Kristalina Georgieva said on Monday aid workers were being increasingly targeted, with 102 killed last year -- more than the death toll among U.N. peacekeepers.

"We cannot continue down this road," she said, promising the EU would present to the UN General Assembly in September a draft resolution on safety and security of aid workers.

"SWAP"

The release appeared to be linked to Mauritania's repatriation to Mali earlier this month of a militant convicted of the kidnapping of Vilalta, Pascual and Gamez, a European security analyst said on Monday.

"There was a swap, though it is unclear if there was also a ransom paid," the analyst said on condition of anonymity.

Officials in Mauritania and Mali have declined to comment on whether the extradition of Omar Sid-Ahmed Ould Hamma, alias Omar Sahraoui, to his home country was linked to efforts to free the hostages.

Mali released four Islamist prisoners earlier this year in an apparent swap for French hostage Pierre Camatte, freed by AQIM in February. Mali was criticized for the move by regional neighbors Algeria, Mauritania and Niger.

The group, which grew out of the Salafist movement in Algeria and has since shifted south into the vast and lawless Sahel, also killed British captive Edwin Dyer last year after London refused to give in to its demands.

Security analysts believe AQIM is less ideological than opportunistic -- raising funds by ransoming hostages and getting involved in drug trafficking.

Algeria, Mali, Mauritania and Niger are trying to improve their cooperation to counter AQIM, which analysts fear could pose a threat to oil and mineral investments in the region.