Four suspected members of the militant Basque separatist group ETA, including its lead explosives expert, were arrested early Saturday in southern France, the Spanish interior minister said.
The three men and one woman were believed to be involved in a deadly December car bombing at Madrid's Barajas airport that killed two people and led to the government ending peace talks with ETA.
It was believed that the four were also involved in a failed attack last week in Castellon, eastern Spain, Interior Minister Alfredo Perez Rubalcaba said.
The four suspects were all armed but offered no resistance when arrested around 6 a.m. in Cahors, near the French city Toulouse, he said.
The minister said the four suspects had been planning new attacks and were found living in a house that also served as an explosives laboratory.
"They were preparing a new car bomb," Perez Rubalcaba said.
Luis Ignacio Iruretagoyena, 50, an alleged ETA veteran, is considered to be ETA's bomb-making expert, the interior minister said.
The other suspects were Ander Mugica, 25, Alaitz Aramendi Jaunarena, 29, and Oihan Barandalla, 31. Mugica fled a police checkpoint in July by jumping out of a taxi, leaving a bag of explosives behind, and Barandalla is thought to be ETA's military deputy, Perez Rubalcaba said.
Authorities blame ETA for a car bombing on Aug. 24 that left two police officers with minor injuries in the Basque town of Durango. The group has not claimed responsibility for the attack.
ETA, whose name is a Basque-language acronym for Basque Homeland Freedom, has killed more than 800 people since 1968 in its campaign for a Basque state.