Madrid  - The trial began Monday in Spain of 27 members of Gestoras Pro Amnistia, an organization defending imprisoned activists of the militant Basque separatist group ETA.

The prosecution at Madrid's National Court accuses Gestoras of acting as an extension of ETA.

Gestoras spokesman Juan Maria Olano told the court in Basque that he refused to answer questions, because the trial was not impartial and because civil and political rights were under "repression" in the Basque region.

Gestoras Pro Amnistia seeks the release of more than 500 ETA members who are serving sentences in prisons around Spain and France.

The prosecution accuses the group of being part of the infrastructure of ETA, which allegedly financed it until 1991. Gestoras was banned 2001.

Gestoras is charged with acting as an intermediary between ETA and its jailed members, keeping them under the group's influence, obtaining from its lawyers information useful for ETA, as well as staging pro-ETA protests and tributes to late ETA activists.

The accused face prison sentences of up to 10 years in the trial, which is to feature more than 250 witnesses. Verdicts are expected in late July.

The trial is seen as part of a strategy of police and judicial crackdowns against the entourage of ETA.

Nearly 50 members of ETA-linked organizations, such as the umbrella organization Ekin and the banned newspaper Egin, were handed prison sentences in December.

Practically the entire leadership of the outlawed party Batasuna was arrested earlier this year. Police and the judiciary have also targeted pro-ETA youth groups that stage acts of street violence.

ETA has killed more than 800 people in its 40-year armed campaign for an independent Basque country, five of them since Socialist Jose Luis Rodriguez Zapatero became prime minister in 2004.

Zapatero, who was re-elected in March, has stepped up the fight against ETA since an attempt to negotiate with the group failed in 2006.

Last week, ETA staged two bomb blasts in the Basque region. One of the explosions caused slight injuries to seven police officers. (dpa)