Mr Barrionuevo is charged with other former senior members of Spain's Socialist party of kidnapping, misappropriating public funds and belonging to an armed group.

They are said to be members of a shadowy armed gang called the Anti-Terrorist Liberation Groups, or Gal.

Mistaken identity

The former Spanish Prime Minister Felipe Gonzalez will be called to the Spanish Supreme Court to testify during the hearing.

The trial will concentrate on Gal's first known action - the 1983 kidnapping of businessman Segundo Marey.

Mr Marey, who was mistaken for an Eta hitman, was released unharmed 10 days later.

Gal is said to have assassinated 28 people they suspected of being Eta members between 1983 and 1987.

It was later discovered that at least a third of them had no connection to the armed group.

Guilty pleas expected

Gal's alleged high-ranking connections came to light after statements made by members of the Spanish security services and a determined investigation by journalists.

It was discovered that leading members of the then-socialist government knew about, funded and, it is alleged, organised what amounted to state terrorism.

Prosecutor Luis Galan said he expected the suspects to admit participation in the kidnapping.

Compensation sought

Mr Barrionuevo, the highest-ranking official on trial for Gal connections, has always denied the charges.

If convicted he and the ex-Secretary of State for Security Rafael Vera face more than 20 years imprisonment.