The Simon Wiesenthal Center has announced a new push to prosecute the last remaining individuals guilty of committing war crimes during the second world war.

The head of the Nazi-hunting organisation's Jerusalem office, Efraim Zuroff, told a press conference in Berlin, the Center would offer a reward of 25,000 euros for information leading to successful prosecution of former Nazi's still at large.

The intiative has been given a boost by the conviction of John Demjanjuk, a Ukrainian former camp guard.

Demjanjuk was convicted purely on the basis of his employment at a concentration camp where over 30,000 Jews were killed, without a proven involvement in individual killings.

"The Demjanjuk case should pave the way for the prosecution of many people who on a daily basis, for an extended period of time, were involved in mass murder," Zuroff said.

Time is running out for prosecutors as perpetrators are dying of old age.

But Zuroff stressed the time that has passed since the crimes should not be a limiting factor.

"We are hoping that this effort will inspire and encourage and motivate faster action.

"The passage of time in no way diminishes the guilt of the killers.

"Old age should not afford protection to mass murders. Each of the victims deserves that an effort be made to find their murderers.

"This society must face up to its responsibility -- there must be no statute of limitations or line drawn under history," he said.