LawyACCUSED war criminal Charles Zentai will take his fight against extradition to the full bench of the Federal Court in an attempt to avoid facing a 65-year-old murder charge in Hungary.

The launch of an appeal came as the 87-year-old avoided being placed in custody yesterday when a Federal Court judge granted a further stay on a ruling last week that he be extradited.

Justice John Gilmour extended the stay until May 11 so Mr Zentai's legal team could obtain a medical report to support an application for bail.

The appeal will present an argument by Mr Zentai that Justice Gilmour was wrong to rule he was eligible for extradition to face allegations he took part in the fatal bashing of a Jewish teenager.

The appeal has frustrated chief Nazi hunter Efraim Zuroff, from the Jerusalem-based Simon Wiesenthal Centre, who said it once again delayed what should have happened years ago. "He's using all sorts of legal tricks to prevent him being put on trial," Dr Zuroff said.

Peter Balazs was a Jewish teenager who was allegedly beaten to death for not wearing the yellow star Jews were forced to display under the Nazi regime.

Mr Zentai denies he took part in Balazs's murder when he was a warrant officer in the Hitler-aligned Royal Hungarian Army.

Mr Zentai has fought his extradition since 2005, when he was arrested at his home in Perth's southern suburbs.

theaustralian.news.com.au