The UN rights office expressed concern Friday about the prosecution of Spanish judge Baltasar Garzon, who is awaiting a verdict in an abuse of power case for probing Franco-era crimes.

"Judges should not be prosecuted for doing their job," said Rupert Colville, spokesman for the UN High Commissioner for Human Rights.

Garzon was tried for ordering an investigation in 2008 into the fate of more than 100,000 people reported missing during the Spanish Civil War from 1936 to 1939, and during General Francisco Franco's rule from 1939 to 1975.

He is accused of violating an amnesty agreed by Spain's main political parties after Franco's death.

"Spain has an obligation under international law to investigate serious violations of human rights that occurred in the past, including those committed during the Franco regime," Colville said.

The spokesman said that under international law Spain is "obliged" to repeal its amnesty law of 1977 in order to investigate past human rights violations including those committed during the dictator Franco's rule.

Spain's high court on Thursday convicted Garzon on a separate charge of wiretapping, barring him from the judiciary for 11 years and effectively ending his career as a judge after he was suspended from his duties in May 2010.

The 56-year-old was found guilty of ordering illegal recordings of corruption suspects talking to their lawyers.

His defenders say vengeful enemies were behind both trials, as well a third case of alleged bribe-taking.

Colville did not comment on Thursday's conviction.