MADRID, Feb 8 (Reuters) - The Spanish High Court banned two Basque parties for three years on Friday because of their links to the separatist guerrilla group ETA, preventing them from taking part in next month's general election.

ETA is a big issue in campaigning for the March 9 elections, and the ruling Socialists are under fire from various quarters for having tried to negotiate with the group, which has killed more than 800 people in its 40-year fight for independence.

The attorney general had asked the High Court to declare the two parties illegal, and the court's ruling against Accion Nacionalista Vasca (ANV) and Partido Comunista de la Tierra Vasca (PCTV) had been widely expected.

The decision will now go before the Supreme Court, which has already banned and declared illegal Batasuna, previously ETA's political wing. Investigators said the ANC and the PCTV had taken over representing the guerrilla group from Batasuna.

"This is not a case of illegalising a political party but taking preventative measures to stop this political party being used to carry out serious crimes," Judge Baltasar Garzon said in the High Court ruling.

Hours before the ruling was handed down, ETA detonated a bomb in the coastal town of Bergara, damaging a courthouse and nearby shops and vehicles but injuring no one.

Garzon ordered that the ANV and PCTV bank accounts be blocked, that the parties stop receiving any state funds and personal donations, and that they close their offices, which the court said were being used by ETA and Batasuna.

The ban, which could be extended for two more years, will not affect the positions members of the two parties already hold in town halls and the regional government in the Basque Country. (Reporting by Inmaculada Sanz; writing by Jane Barrett; editing by Tim Pearce)

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