Mr Argana was murdered in March 1999

The decision by the 11-member court was unanimous, agreeing that Mr Oviedo was the victim of a political persecution, freeing him from jail and allowing him to stay in Brazil.

Mr Oviedo's lawyers have welcomed the decision, saying he would not receive a fair trial in Paraguay, and that his life would be in danger if he returned there.

Assassination

Paraguayan authorities want Mr Oviedo to stand trial for allegedly masterminding the assassination of the Mr Argana, in March 1999.

The general denies the charge.

The former army chief was captured in Brazil, at Foz de Iguazu near to the Paraguayan border, on 11 June last year, after months on the run.

He was found with a revolver and 10 mobile telephones.

Coup conviction

Mr Oviedo also led a failed 1996 coup attempt in Paraguay against President Juan Carlos Wasmosy for which he had been sentenced to 10 years in prison.

Mr Oviedo's opponents in Paraguay say he must still serve out that sentence if he returns to Paraguay.

Mr Oviedo has claimed he is the victim of political persecution and said last month he would return voluntarily to Paraguay to face the accusations.

In response to the decision, Mr Oviedo's wife, Raquel Marin, who is in the Paraguayan capital Asuncion, said the court's decision "validates our suffering."

"I am so emotional and I have so much faith that there with be justice," she said.