AFP - Three Spanish humanitarian workers were kidnapped in northwestern Mauritania on the road linking the capital Nouakchott to the city of Nouadhibou, officials and aid workers said.

The three Spanish nationals, "two men and a woman, were travelling in a car, the last vehicle of a convoy that was heading from Nouadhibou to Nouakchott" when they were attacked on Sunday afternoon, a Spanish diplomat said.

The convoy had earlier delivered aid to Nouadhibou and was transporting donations that they intended to drop off in various towns along the route, the diplomat added.

A Mauritanian security source confirmed the kidnapping, adding the kidnappers fired several shots to force the vehicle to stop and then took the Spaniards away in a 4x4 vehicle.

A spokesman for the Spanish humanitarian group Barcelona-Accio Solidaria confirmed the three were members of their association and named them as Albert Vilalta, Alicia Gamez and Roque Pascual.

"The found all the supplies only the people were gone," said the spokesman, adding "we don't know anything more, if they were bandits or had any political motives."

A Spanish humanitarian worker based in Mauritania, Montse Bosch, was able to speak by telephone with some of the other members of the aid convoy following the kidnapping.

"A group of armed men stopped and then took them, leaving their vehicle in place and without touching any of the supplies, luggage or money contained in the car," she said.

Bosch said Barcelona-Accio Solidaria is part of the Caravana Solidaria, or Solidarity Caravan, which distributes aid in Mauritania and other African countries in the region.

The attack took place near the town of Chelkhett Legtouta, 170 kilometres (106 miles) north of Nouakchott, according to the Mauritanian security source.

Mauritanian army units in the area were searching for the kidnappers, the source added, and reinforcements had been sent to the area.

Mauritania, a vast country of three million people, has been hit by a number of attacks since 2007 claimed by the north African branch of Al-Qaeda.

The incident came days after a French citizen was kidnapped in the northeast of neighbouring Mali, which according to a Malian security source are being held by Al-Qaeda militants.

Several Westerners have been kidnapped in recent months in Africa's Sahel region and transported to northern Mali before being freed.

In June, however, the Al-Qaeda militants announced on a website that they had beheaded Briton Edwin Dyer because London would not meet their demands. It was believed to be the first time the group had killed a Western hostage.