Madrid - Spain's National Court on Friday prevented the opening of dozens of mass graves dating from the 1936-39 civil war and General Francisco Franco's ensuing 36-year dictatorship.

The court accepted a complaint by prosecutors trying to block the orders issued by Baltasar Garzon, a judge at the same court.

Garzon has launched Spain's first judicial investigation into the fate of Franco opponents killed in acts of repression during the war, which was unleashed by Franco's uprising against the republican government, and the dictatorship.

Garzon authorized the opening of 19 mass graves containing remains of Franco's victims, including one believed to hold the bones of poet Federico Garcia Lorca.

A judge representing Garzon subsequently ordered the opening of other graves in six locations, including the Valley of the Fallen, Franco's huge mausoleum near Madrid, where tens of thousands of republicans and Francoists also lie buried.

It was not yet clear whether Garzon was competent to investigate Franco's crimes, and he thus had no right to give orders that would be difficult to reverse, the public prosecutor's office argued.

Garzon, who has investigated human rights crimes in Latin America, estimates the number of Franco's victims at more than 100,000.

The Franco regime paid tribute to Francoists killed in the war, but tens of thousands of republicans were left in mass graves.

Private associations have exhumed and given burials to thousands of people in the recent years.

The prosecutors oppose Garzon's view of Franco's abuses as crimes against humanity, and argue that they were covered by a 1977 amnesty granted to the dictator's collaborators.

Spain's conservative opposition has criticized Prime Minister Jose Luis Rodriguez Zapatero's Socialist government's attempts to rehabilitate the memory of Franco's victims, accusing the government of reopening old wounds. (dpa)