It was the first public admission by an Iranian official that Kazemi, who died on 10 July more than two weeks after her arrest, suffered her fatal injuries while in custody.
“The high possibility is that her murder was caused by a haemorrhage caused by a blow (to the head),” said Abtahi.
An initial government inquiry found that Kazemi died of a brain haemorrhage caused by a blow to the skull. But it did not establish whether the blow was deliberate or who may have caused it.
Further investigations are underway and five security agents have been detained in connection with the case.
Kazemi’s mother was quoted on Wednesday as saying she buried her daughter in Iran against her will.
The burial of Kazemi, a Montreal-based photojournalist of Iranian descent, has caused a diplomatic storm between Tehran and Ottawa, which wanted her body returned to Canada.