A small bomb exploded at a popular holiday resort on the Costa del Sol in southern Spain early on Tuesday but caused no injuries or damage, government officials said.
The bomb went off just past midnight in the sand next to the Torremolinos beachfront walkway. One person was treated by emergency services for shock after the blast, Spain's El Mundo newspaper website said.
The blast followed four small explosions at holiday resorts on Spain's northern coast on July 20 which local authorities blamed on Basque separatists ETA.
There was no warning call and no one claimed responsibility for Tuesday's explosion, said government spokesman Juan Jose Lopez Garzon.
He had no information anyone had been injured by the blast near the la Carihuela walkway in Torremolinos, which left a metre-wide hole in the sand.
"There was practically no damage," said the spokesman.
Guests at nearby hotels felt their rooms shake, and some were badly frightened, El Mundo reported, citing hotel staff.
Government officials said they remained on alert over possible ETA attacks.
"We have been on alert level 2 for some time and we will remain on this," said Lopez Garzon.
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.
{{/usCountry}}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.
{{/usCountry}}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 bombed Spanish resorts during the busy summer holiday season to target Spain's tourist industry.
The separatist guerrillas have killed over 800 people in their four-decade fight for an independent Basque homeland. Polls show most Basques do not want their own state.