Ephraim Zuroff, chief Nazi hunter of the Simon Wiesenthal Centre, has labelled a Budapest court's decision to acquit an accused Nazi war criminal who was convicted in absentia decades ago a "miscarriage of justice".

Sándor Képiró, 97, was acquitted in the Buda District Court this week of all charges arising from a 1942 massacre of 1,250 Jews, Serbs and Roma. The state prosecutor immediately appealed against Judge Béla Varga's decision.

The verdict "was in my view founded on flawed legal premises", said Hungarian Jewish leader Péter Feldmájer.

The case was based largely on documentation Mr Zuroff had provided to state prosecutors in 2006. Képiró's lawyer filed a libel suit against Mr Zuroff last autumn, accusing him of proclaiming his client guilty. That suit was put on hold when the trial against Képiró opened, but Mr Zuroff said on Tuesday that his lawyer believed "the acquittal should not affect the libel trial".