The Spanish interior ministry says at least 15 suspected members of the armed Basque separatist group Eta have been arrested in north-eastern Spain.
More than 150 police officers were involved in the raids
More than 150 Spanish police conducted pre-dawn raids in the three Basque provinces and neighbouring Navarra.
Eta has suffered serious setbacks in recent months, since French and Spanish police stepped up joint operations.
On Sunday the banned Basque political party Batasuna called for a peaceful dialogue with the Spanish government.
But Batasuna leader Arnaldo Otegi stopped short of launching an anticipated appeal for Eta to end its terror campaign.
As it never explicitly condemned Basque separatist violence, the party was made illegal 20 months ago by Spain's Supreme Court.
French and Spanish police have arrested more than 100 Eta suspects on both sides of the border so far this year.
Most of the group's leaders have been detained and its caches of weapons and explosives seized.
Commenting on the latest arrests, Spain's Deputy Prime Minister, Maria Teresa Fernandez de la Vega, said Spaniards could see that "the action against the men of violence is effective".
Eta has in the past announced a dozen ceasefires, all of which it has broken.
The longest ceasefire held for 15 months between 1998 and 1999.
Eta carried out its last attack on Saturday, but no-one has been killed in an Eta attack in more than 17 months.
This has been the quietest period in the group's history, barring truces, since the early 1970s.