PARIS: French anti-terror officers stormed an apartment in an Alpine ski resort in a dawn raid Wednesday and seized three suspected militants from the Basque separatist group ETA.

Shortly after the swoop, French police found a weapons cache holding more than 100 kilos (220 pounds) of explosives hundreds of kilometres away, Spain's Interior Minister Alfredo Perez Rubalcaba told reporters in Madrid.

He named the suspects as Alberto Machain -- whose photograph was circulated in July following a deadly bomb attack on a police barracks in Palma de Majorca -- alleged senior ETA leader Aitzol Etxaburu and Andoni Sarasola.

French officials said the three-man cell, who were armed with handguns and carried false identity papers, were surprised in a flat in an 18-storey accommodation block in Le Corbier Villarambert in the Savoie region.

Around 20 heavily-armed officers from the RAID special weapons squad, backed up by detectives from Lyon, stormed the flat just before dawn and fell upon the suspects as they slept, they said.

"They had no time to resist," a judicial official told AFP.

In all, four handguns, 40 detonators and several electronic devices that could be used in making bomb triggers were found in the flat, along with a large quantity of paperwork, a French investigator told AFP.

After the detainees were taken away, detectives began a search of the apartment. Reporters were barred from the Lunik Orion building, but black vehicles and a masked RAID officer could be seen outside.

"When we opened our shutters we could see everyone milling about -- men in black, people in masks," said Jean-Marie Renault, a retiree who owns a holiday home in the block.

"I was woken at around 6.30am by a dog barking as it sniffed around a brown van. I saw masked men and a break-down truck that they used to take away the vehicle," said his retired neighbour Anne-Marie Boyer.

The operation was carried out after several months of inquiries by French anti-terror police in cooperation with the Spanish security service, officials on both sides of the border said.

Rubalcaba said the arrests led police to an ETA hideout in the French town of Ferrieres, about 40 kilometres (60 miles) from the Spanish border, where they found 100 kilos of ammonium nitrate and 12 litres of nitromethane.

All three ETA suspects are "top members of the military wing ... responsible for supplying weapons, ammunition and explosives to armed cells," he said.

Founded half a century ago, ETA is blamed for the deaths of 828 people in its violent campaign for an independent Basque homeland in part of northern Spain and southwest France.

It figures on several terrorist blacklists, including those of the European Union and the United States.

Traditionally, ETA has concentrated its attacks on Spanish targets while its militants use France as a rear base to hide out and rearm. In recent years French officials have arrested several senior suspects.