The truth commission investigating abuses under Brazil's military dictatorship Tuesday branded as "insufficient" the armed forces' acknowledgement of possible rights abuses, calling for greater transparency.

The Commission had demanded in August that all branches of the armed forces either confirm or deny involvement in "cases of torture, death and disappearance" during military rule between 1964 and 1985.

Last week, the armed forces responded, admitting for the first time that they had no grounds to deny a list of 24 serious rights violations during the military regime.

But, in a statement on its website, the commission said the armed forces' reaction was "insufficient," as they did not "clearly and unequivocally" state their responsibility.

The commission added it was "essential that the ministry of defense and chiefs of staff move on from the non-denial of human rights violations at military installations to recognition the armed forces were implicated."

The commission had detailed the cases using evidence from judicial proceedings, public ministry documents and police investigations.

Unlike its South American neighbors, Brazil has not prosecuted military officials for regime-era crimes, a 1979 amnesty law preventing it from doing so.

The country has officially recognized some 400 deaths or disappearances under the military regime -- compared with 30,000 deaths in neighboring Argentina and more than 3,200 in Chile.

President Dilma Rousseff, who as a former guerrilla was herself tortured under the regime, signed off on a 2012 law creating the commission, which can summon witnesses under oath but not bring any prosecutions.

The commission is due to unveil its final report in December.