AFP - French police have discovered a cache of bomb making materials following the arrest of three suspected Basque separatists on Wednesday, the Spanish government said.

Interior Minister Alfredo Perez Rubalcaba said the three were all "top members of the military apparatus" of the armed Basque separatist group ETA and responsible for "supplying arms, ammunition and explosives" to the commandos.

Prime Minister Jose Luis Rodriguez Zapatero hailed the arrests as "a new demonstration of the strength and effectiveness of the fight against terrorism.

"We will continue to eradicate this unacceptable and intolerable stain of violence and terror," he told a news conference.

French anti-terror officers seized the three after storming an apartment in an Alpine ski resort of Le Corbier Villarambert in a dawn raid Wednesday.

Rubalcaba identified them as Alberto Machain, Aitzol Etxaburu and Andoni Sarasola.

He said police found four revolvers, 42 detonators and about 20 plastic casings to be used for bombs at the flat. The suspects also had a van that had been reported stolen in France in June.

The arrests also led police to an ETA hideout in the town of Ferrieres, about 40 kilometres (60 miles) from the Spanish border, where they found 100 kilogrammes (220 pounds) of ammonium nitrate and 12 litres of nitromethane used to make bombs, the minister told a news conference.

Machain's photograph was circulated following a deadly bomb attack on a police barracks in the resort island Majorca on July 30.

But Rubalcaba said there was "no evidence" linking any of the three to that attack or others in recent weeks in Majorca and in the northern city of Burgos.

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.