Bulgaria's chief prosecutor has asked the country's highest court to revoke the parole a lower court granted to Australian Jock Palfreeman who was convicted of fatally stabbing a Bulgarian student during a 2007 brawl.
Palfreeman had served 11 years of his 20-year prison sentence when a three-judge Court of Appeals panel unexpectedly ordered him freed on Thursday.
The 33-year-old left prison the same day but was transferred to an immigration detention facility to await a new passport from the nearest Australian embassy which is in Athens.
While there has been rejoicing in Australia, in Bulgaria the news of his release has been met with outrage.
Prosecutor-General Sotir Tsatsarov has petitioned Bulgaria's Supreme Court of Cassation to suspend Palfreeman's parole and review the panel's ruling.
Palfreeman's lawyer, Kalin Angelov, called the prosecutor's appeal "absurd" and advised Australian authorities to speed up efforts to fly the Australian home.
Australia's Department of Foreign Affairs and Trade would only say it is continuing to provide consular assistance.
"Owing to our privacy obligations we will not provide further comment," a statement from DFAT said.
Palfreeman has maintained he acted in self-defence when he intervened to prevent law student Andrei Monov, 23, and a group of friends from attacking two Roma, or gypsy, men.
Interior Minister Mladen Marinov on Sunday defended the decision to release Palfreeman.
"The logic of the law is to find justice and make it quick, have an effective sentence," he said.
