A parking lot at Madrid's airport was wrecked by a car bomb explosion Saturday morning, signaling the demise of a nine-month-old cease-fire committed by the Basque separatist group ETA.

The bomb went off at about 9:30 a.m. (0830 GMT) at the airport's new Terminal Four. Prior to the explosion, the authorities received two warning phone calls, one of which was allegedly from the ETA.

Shortly after the incident, Interior Minister Alfredo Perez Rubalcaba said the ETA's act had broken its cease-fire commitment.

Two police officers suffered slight injuries, the authorities said.

The ETA, which wants to achieve independence for the Basque Country, a region that straddles northeastern Spain and southwestern France, has killed 850 people in its separatist activities since 1968.

It announced a "permanent ceasefire" on March 22. Three months later, Spanish Prime Minister Jose Luis Rodriguez Zapatero said his government would begin talks with the armed separatist group, but he would never accept the independence of the Basque region.

The process has also been strained by regular politically motivated vandalism by ETA supporters and by a weapons robbery in France, which the government suspected was carried out by the guerrillas.

The ETA threatened last month that it will put an end to its peace process with the government if no progress is achieved in the coming days.

 Editor: Yan