The 1977 amnesty was granted two years after Gen Franco's death
Spanish prosecutors have asked the high court to stop an investigation into atrocities during Gen Franco's rule, saying they are covered by an amnesty.
Judge Baltasar Garzon last week began investigating what happened to thousands of people who vanished during and after the civil war.
But chief prosecutor Javier Zaragoza said a 1977 amnesty covered the crimes.
A ruling on the appeal could take two months, but the inquiry can continue in the meantime.
The 1977 amnesty law, passed two years after Gen Francisco Franco's death, was to help Spaniards put the country's divisions behind them.
The civil war was triggered by the military uprising of Gen Franco, whose supporters are said to have systematically eliminated left-wing opponents, even after the war was won in 1939.
Mr Zaragoza said in a statement on Monday that the offences were not crimes against humanity as Judge Garzon claimed.
Instead, they should be considered ordinary crimes under the criminal code effective when the war broke out in 1936, Mr Zaragoza said. The statute of limitations has expired for such crimes.
An 18-judge National Court panel will decide if Judge Garzon can continue, but in the meantime the exhumation he ordered of 19 mass graves can proceed.
Last week in his 68-page ruling, Judge Garzon said Francoists carried out "illegal permanent detentions" which he says falls within the definition of crimes against humanity.
He referred to 114,000 people who disappeared during a 15-year period after the outbreak of war in 1936.
Judge Garzon's document names Gen Franco and 34 of his senior aides as the instigators of the alleged crimes.
The judge has also asked Spain's interior ministry to provide names of senior members of the fascist Falange Party, which supported Gen Franco, with a view to possible prosecutions.