Spain’s prime minister apologized Monday for putting his faith in a Basque peace process that collapsed in a thunderous and deadly car bombing, but insisted he was right to have sought negotiations with separatist militants and appealed to his political foes for unity at a time of crisis.

In a speech to parliament often interrupted by jeers and grumbles from conservative lawmakers, Jose Luis Rodriguez Zapatero did not announce any concrete new measures against the armed separatist group ETA. He said police pressure and court trials continued during the now-ended ETA cease-fire and will proceed as usual.

The Socialist leader said that with the Dec. 30 bombing in Madrid, ETA had shattered a 9-month cease-fire and a nascent peace process.

Opposition leader Mariano Rajoy wasted no time in attacking Zapatero, saying as he took the podium that the premier had lost all credibility for saying less than 24 hours before the bombing that the peace process had left Spain better off than it was a year ago and that even better times awaited it.