Fourteen suspected Islamic militants arrested in Spain on Saturday may have been planning a terrorist action in Barcelona, the interior minister said.
Interior Minister Alfredo Perez Rubalcaba said more arrests were expected and the country was on high security alert.
The arrests in Barcelona were prompted by information from several unspecified European intelligence agencies, and there was evidence the suspects — 12 Pakistani nationals and two people from India — could have been planning "a terrorist action" in the northern city, he told a news conference.
Rubalcaba said police found four timers.
"When someone has timers at home you have no option but to think violent acts are being planned," he said.
Civil Guard officers made the arrests as part of raids planned with the National Intelligence Center, the Spanish equivalent of the CIA, Rubalcaba said. Five homes were searched overnight he said.
Prime Minister Jose Luis Rodriguez Zapatero confirmed the arrests and said investigations were continuing.
Europe's worst Islamic-linked terror attack took place in Spain on March 11, 2004, when bombs went off in railway carriages during the morning rush hour near Madrid's Atocha station. The attack killed 191 people injured more than 1,800. Twenty-one people have been convicted of involvement in that attack.
Since the Sept. 11, 2001, attacks in New York and Washington, Spanish police have arrested hundreds of Islamic terrorism suspects, many in connection with the Madrid attack.
In recent years police have also focused on cells suspected of recruiting mujahedeen fighters and suicide bombers, or of collecting money to finance Al-Qaida-linked groups abroad.
The Madrid train attacks were claimed by Muslim militants who said they had acted on behalf of al-Qaida to avenge the presence of Spanish troops in Iraq, but Spain's courts found no evidence al-Qaida ordered or financed the attacks.