MADRID (CNN) -- The Supreme Court on Wednesday sentenced former Interior Minister Jose Barrionuevo and his deputy to 10 years each in prison for their involvement in what is known as the "dirty war" waged against the Basque separatist guerrilla group ETA in the 1980s.

Supreme Court Justice Joaquin Delgado said the 11-member court found Barrionuevo, former Secretary of State Rafael Vera and former Civil Governor Julian Sancristobal guilty of misuse of public funds and kidnapping.

The ruling was in connection with a mistaken-identity kidnapping in 1983, when Basque businessman Segundo Marey was kidnapped after he had been mistakenly identified as an official of ETA.

The botched kidnap marked the beginning of a secret campaign of terror against alleged ETA guerrillas in the 1980s.

Reporter Al Goodman on reaction to the verdict AIFF or WAV (383 K / 33 sec. audio)

The dirty war scandal was seen as a major factor behind the defeat of then-Socialist Prime Minister Felipe Gonzalez in the 1996 general election.

At the time, respected news media accused Gonzalez of involvement in the undercover operation, which was run by a group known by the Spanish initials GAL.

Authorities say GAL was a front for security forces and hired assassins paid with secret government funds.

When the kidnapping took place, Barrionuevo was Interior Minister under Gonzalez. Both Barrionuevo and Vera claimed innocence, saying they were not involved with the "dirty war."

Sancristobal, the former civil governor of the Basque province of Vizcaya, where Marey was held for 10 days even after his captors realized he was not actually an ETA member, admitted his involvement in the kidnapping.

However, he said the orders had come from higher up.

Barrionuevo and Vera were accused of masterminding the activities of the Anti-Terrorist Liberation Groups, which appeared for the first time after the Marey kidnapping.

The shadowy organization killed 28 people between 1983 and 1987, many of them with no connection to ETA separatists.

ETA, or Basque Homeland and Freedom, is said to have killed 800 people in its 30-year campaign for Basque independence.

During the "dirty war" trial, which ended earlier in July, Gonzalez denied under oath that he had authorized the undercover war.

Some commentators have called for the former premier, who is believed to be eyeing a post as president of the European Union's executive Commission, to retire from politics.

Correspondent Al Goodman and Reuters contributed to this report.

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