A small explosive device went off early this morning near the la Carihuela walkway in Torremolinos.

The bomb which detonated at just past midnight left a metre-wide hole in the sand.

One person was treated by emergency services for shock after the blast.

There was no warning call and no one has claimed responsibility for the explosion.

Guests at nearby hotels felt their rooms shake, and some were badly frightened.

Spanish police have been watching for possible attacks in the Andalucia area of southern Spain, popular among British holidaymakers, after they arrested members of an ETA unit and found evidence they were planning attacks in the region.

Torremolinos Mayor Pedro Fernandez Montes played down the attack and called on tourists not to panic. "Obviously people are frightened ... above all the British tourists. You know what the English tabloids are like, they exaggerate everything, and say there's been a bomb on the Costa del Sol, when really it wasn't a bomb.

There's just a little hole in the sand, something that's not very big," Fernandez Montes said on Spanish National Radio.

ETA has often targeted Spanish resorts in an attempt to affect Spain's tourist industry. The separatist guerrillas have killed over 800 people in the last 40 years. They only have minority support for a Basque homeland in the northern provinces where their struggle is based.