Pamplona - Seventeen people were injured on Thursday in a car-bomb attack in the northern Spanish city of Pamplona, local authorities reported.

A vehicle exploded in a car park in the grounds of the University of Navarra in Pamplona, capital of the Navarra province which borders on the separatist Basque region.

Witnesses said several vehicles were set on fire by the explosion, and nearby buildings were substantially damaged.

State-owned radio station RNE reported that the injured mostly suffered from lacerations caused by flying shards of glass. Police evacuated university buildings and cordoned the area off following the blast.

An anonymous caller had warned of the blast to police one hour before it detonated. However police took no action due, they said, to the fact that the caller gave no precise information about where the bomb was to be found.

RNE radio said it was a "great wonder" that no one was killed in the attack.

Spanish police Tuesday arrested four individuals in Pamplona who were suspected of belonging to the underground Basque separatist group ETA, and were thought to be planning an attack in the region.

ETA is listed as a terrorist organization by the European Union and the United States.

Bomb and arson attacks believed to be the work of ETA damaged two train stations in Spain's Basque country on Saturday, without causing injuries. (dpa)