Spanish police detained nine suspected militants of the ETA movement in the Basque town of San Sebastian yesterday.
The arrests come less than 24 hours after French police arrested Jose Javier Arizcuren, ETA's military chief, and five other suspected terrorists in Paris. The culmination of two years of detective work by Spanish and French police, they are the first important police operations against ETA since it declared a unilateral truce six months ago.
The ceasefire announcement last September was hailed by many as the tentative start of a peace process after a 30-year terrorist war which has caused some 800 deaths. While there have been no fatalities since its declaration, there has been almost daily street violence in Basque towns against private property and businesses.
Many fear these latest detentions could endanger the ceasefire. "The government of the Popular Party will be responsible for any consequences," warned Mr Arnaldo Otegi, the leader of ETA's political wing HB.
Mr Jaime Mayor Oreja, the Spanish Interior Minister, welcomed the news of the arrests and said he was confident the ceasefire was not in danger. "The government only wants peace, without pressure or conditions," he said.
There have been increasing demands by the nationalists, and not only those allied to ETA, to begin talks with the separatists and bring Basque prisoners to jails close to their homes. But in spite of helpful words by the Madrid government, negotiations have yet to start and only a handful of prisoners have been moved.
Mr Arizcuren, alias Kantauri, is alleged to be responsible for some 20 murders and the planning of other terrorist attacks, including the assassination plot against King Juan Carlos and the attempt on the life of then leader of the opposition, Mr Jose Maria Aznar, now Prime Minister, in 1995.
Mr Arizcuren is believed to be a member of the hard-line faction of ETA opposed to the ceasefire.