MADRID, Sept 22, 2008 (AFP) - A Spanish soldier was killed and another injured Monday when a car bomb exploded outside a military school in the country's north in a third attack attributed to Basque separatists in 24 hours.

'One person was killed and another hospitalised,' said a government source in the autonomous Cantabria region, where the blast occurred, which is adjacent to the Basque Country.

The source added that the life of the injured soldier was not in danger and identified the officer killed as Luis Conde de la Cruz.

The Basque region's road assistance service received an anonymous telephone warning 35 minutes ahead of the explosion in the early hours of Monday, a spokesman for the service said. The call claimed the attack on behalf of the militant Basque separatist group ETA.

The blast caused 'considerable material damage' according to police in Santona, which lies in the Cantabria autonomous region.

De la Cruz is the fifth person killed in attacks suspected to be the work of ETA since the organisation ended a 'permanent ceasefire' in June 2007.

Spanish Defence Minister Carme Chacon and Interior Minister Alfredo Perez Rubalcaba were expected to visit the site of the blast later on Monday, according to Cantabria regional officials.

Monday's car bomb attack follows two suspected ETA car bomb attacks the previous day.

Ten people were injured after suspected Basque separatists threw petrol bombs at a police station in Ondarroa in northeast Spain to lure officers outside before detonating a car bomb.

That attack came only hours after a car bomb exploded in the regional capital of Vitoria, causing no injuries as an anonymous warning gave police time to clear the area.

Each bomb used around 100 kilos (220 pounds) of explosives.

If confirmed to be the work of ETA, the latest blast would take the number of killings attributed to the group to 824 people since it launched its campaign of violence 40 years ago.

Designated a 'terrorist organisation' by the European Union, the group has carried out a series of bombings, mostly in the northeastern Basque region, since talks with the government collapsed in 2007.

Its last victim was a policeman who was killed when a car bomb exploded in front of his barracks in the Basque Country on May 14.

Spanish police have detained dozens of suspected members of ETA and its supporters in recent months and Prime Minister Jose Luis Rodriguez Zapatero has repeatedly ruled out any further talks with the group.

Spanish authorities have also moved against parties with links to ETA's outlawed political wing Batasuna.

The country's Supreme Court recently banned a Basque independence party linked to ETA's outlawed political wing.

The high court voted unanimously to ban the Basque Nationalist Action (ANV) party in a decision based on a 2002 law allowing the exclusion of parties that back terrorism.

The Basque regional government's plans to hold a referendum on self-determination for the wealthy northeastern region has also been declared unconstitutional by Spain's Constitutional Court.