"Death was due to asphyxia as a result of ante-mortem suicidal hanging. Vaginal smear was taken and on microscope it did not reveal presence of spermatozoa," according to the detailed post-mortem report conducted by doctors at the Silchar Medical College.
The report also pointed out that there was "no finding suggesting recent sexual intercourse", a senior district administration official said.
The bodies of the girls - one a class 10 student and another a class nine student - were found hanging from a tree from a same rope at Dalgram village in Nilambazaar police station area on Thursday.
The family members of the girls, both friends, had refused to file an FIR, a senior police official said.
According to initial investigation, the official said, it was suspected that the girls had committed suicide after their family's opposition to their having affairs with two youths of the area.
The death of the girls had created a sensation in the area with a section of the local people alleging that the girls had been raped and hanged, even though the family members had made no such allegation, he said.