According to The Australian daily, Vasiiljkovic, also known as Captain Dragan and as Daniel Snedden, "has filed a fresh claim in the Federal Court, alleging Croatia is seeking to question him for offences under criminal legislation that did not exist at the time the crimes were allegedly committed."
Following the claim of Vasiljlkovic, who is currently in Silverwater prison in Sydney, a directions hearing will be held in the Federal Court next Wednesday.
The 55-year-old former Serb paramilitary was arrested this May after being on the run 43 days, since the Australian High Court cleared the way for his extradition in Croatia.
The Croatian authorities sent a request for his handover in 2006.
Vasiljkovic is suspected of war crimes committed against captured Croatian soldiers and police in Knin and Bruska in February 1993, and of war crimes against civilians.
Vasiljkovic's Sydney barrister, Clive Evatt QC was quoted by The Australian as saying that the relevant sections of Croatia's criminal code were retrospective in this case.
"But you cannot be an extraditable person based on retrospective legislation," the barrister said.
Croatian sources told The Australian that "the relevant elements of the basic criminal code were offences under previously existing Croatian law."
"The sources said the March 1993 legislation was merely a conversion into the newly formed republic of Croatia's criminal code of laws that existed in the former Yugoslavia," reads the article in the Australian.