MADRID, Spain (CNN) -- Spain's spy agency chief said Tuesday a suspected double agent had been arrested who revealed the names of Spanish spies and other state secrets to a foreign nation.
Spain's SER Radio reported the recipient nation was Russia.
The suspect, Robert Flores Garcia, was arrested Monday morning at his home on Tenerife Island in Spain's Canary Islands. He passed secrets in exchange for hefty payments from December 2001 to February 2004, said the spy chief, Alberto Saiz, head of the National Intelligence Agency (known by its Spanish initials CNI).
Saiz, at a news conference, refused to publicly identify the recipient country, but Spain's SER Radio, said it was Russia, citing unnamed sources.
Flores, a Spanish Civil Guard assigned to spy agency headquarters for internal matters, had been a suspect under surveillance by Spanish intelligence since July 2005, said Saiz.
Flores resigned from his position at the spy agency in January 2004, Saiz said.
Saiz insisted that Spain's national security was never threatened, nor, he said, was there a threat to security at NATO and the European Union. Spain is a member country of both organizations.
But Saiz said the alleged revelations of the suspected double agent forced Spain to substitute a number of its spies.
The suspect allegedly revealed the names of dozens of Spanish spies, possibly including the seven Spanish spies killed in an ambush south of Baghdad in November 2003, Saiz said.
An eighth Spanish intelligence agent traveling with them survived. The eight spies, were in Iraq to provide intelligence for Spanish troops who were stationed at the time in Iraq as part of the U.S.-led coalition. The spies were traveling in two vehicles when insurgents launched an ambush with automatic weapons and rocket-propelled grenades.
Flores is suspected of transferring classified material and could face 12 years in prison if convicted, Saiz said.
Saiz spoke at a rare news conference in Madrid, which some Spanish media said was the first ever offered by Spain's intelligence chief.
Saiz said the alleged betrayal occurred at a time when Spain's spy agency was not fully prepared to deal with an inside mole. E-mail to a friend
CNN's Al Goodman contributed to this report.