An explosive device placed inside a car in northern Spain failed to explode Sunday night, police saying the Basque separatist group ETA is responsible for the attempted attack.

The vehicle was parked near a government building in Logrono, the capital of La Rioja region in northern Spain. Thirty minutes before the bomb was scheduled to be detonated the Basque newspaper Gara received an anonymous call which warned about the attack.

Only a small explosion occurred, no casualties or considerable material damage being reported. According to police experts, approximately 80 kilos of explosives and a container filled with fuel were attached to the vehicle’s floor.

Apparently, a detonator malfunction prevented the bomb from exploding with full force. The car and explosives were seized by the police and activity resumed as usual in the region Monday morning.

Previously, ETA threatened it will continue the campaign against government representatives “on all fronts.” The group blamed the Socialist government for the failure of last year’s peace talks.

For six months government officials and ETA representatives held ardous negotiations, but the process ended on December 30, when a car bomb took two lives at Madrid airport.

ETA ended a 14-month ceasefire in June and since then several attacks occurred, all being claimed by the armed nationalist organization. Two police officers were injured last month when a car bomb went off near a barracks in northern Spain.

Security forces managed to prevent several other attacks by arresting members of the guerrilla group and seizing large quantities of explosive substances.

Also on Sunday, ETA supporters clashed with police forces on the streets of the Basque city of San Sebastian. Five policemen and six protestors were injured, security forces detaining nine ETA supporters after the street scuffles.