The armed Basque separatist group ETA claimed responsibility for the killing of a civil guard in a bomb blast this month, in a statement on Friday which said its attacks would go on.

ETA said it carried out the bombing which killed 41-year-old Juan Pinuel Villalon at a civil guard headquarters on March 14, as well as three other attacks, in a statement sent to the pro-independence Basque newspaper Gara.

It also referred to the May 22 arrest in Bordeaux, southwestern France, of ETA's reputed leader, Javier Lopez Pena, saying it was in line with 'the repressive strategy of the French and Spanish states to hunt down ETA militants and officials.'

A booby-trapped van exploded outside a civil guard barracks in Spain's restive Basque country on May 14, killing Pinuel Villalon and wounding four other members of the paramilitary police force.

ETA, whose initials stand for Euskadi ta Askatasuna, or Basque Homeland and Freedom in the Basque language, is considered a terrorist organisation by the European Union and the United States.

It is blamed for the deaths of more than 820 people in its 40-year campaign for an independent Basque nation in northern Spain and southwestern France.

Friday's statement accused Paris and Madrid of seeking to 'strangle the liberation movement' by 'striking all those who back real political change and those who fight.'

It warned that attacks would continue if 'no adequate response is found to resolve the basic problem.'

It also scoffed at a controversial plan for a referendum on self-determination for the Basque people out forward by the head of the Basque regional government, Juan Jose Ibarretxe.

The Socialist government in Madrid has rejected the poll, planned for October 25, as illegal and is to take the issue before the Constitutional Court.

ETA said Ibarrexte's moderate Basque Nationalist Party and the Socialists were engaged in a 'shameful game' in the run-up to next year's regional elections and had 'nothing sensible to put forward.'

As well as the explosion which killed Pinuel Villalon, ETA also claimed responsibility for blasts on May 1 at San Sebastian and Arrigorriaga, and on May 19 in the port of Getxo, all in the Spanish Basque Country.