17-year-old Samra and her friend, 15-year-old Sabina, travelled to Syria together last year to join Isis - both are now believed to be dead.
Reports in the Österreich and Kronen Zeitung tabloids cite ‘insider' sources who say Samra was beaten to death but the interior and foreign ministries have not confirmed this.
"We cannot comment on individual cases," Foreign Ministry spokesman Thomas Schnöll told the Austria Press Agency. Interior Ministry spokesman Karl-Heinz Grundböck also said that he could not comment on the matter.
The report in the Kronen Zeitung quotes a Tunisian woman who also travelled to Syria to join the jihadists last year but later escaped and returned home. She told the newspaper that she lived with Samra and Sabina in Raqqa.
Rumours about the girls' fate also circulated late last year, with an Israeli expert from the UN saying that one had been killed fighting in Syria and the other had disappeared.
Photos of both girls appeared on social networking sites, with them holding Kalashnikov rifles and surrounded by armed men - images which Austrian police said were meant to recruit young girls to join Isis.