* Critic of Austria's slowness in returning Nazi booty
* Convicted in Austria of fraud in restitution claim
* Acted for Holocaust survivor mother, denies wrongdoing
By Derek Brooks
VIENNA, April 4 (Reuters) - A Jewish critic of Austria's post-war record in returning property plundered by the Nazis plans to take his case to the European Court of Human Rights after receiving a jail sentence last year when his own restitution claim went sour.
Stephan Templ, 53, an architectural historian living in Prague, was sentenced to three years in jail for defrauding the Alpine republic after failing to name his aunt in a restitution claim for a hospital building near Vienna's famous Ringstrasse.
The state argued that the aunt, Elisabeth Kretschmer, could have relinquished her stake in the building, which was seized from its Jewish owner after Nazi Germany's annexation of Austria in 1938, and that this share would have reverted to the state.
Kretschmer learned in 2011, two years after a state panel returned the building to dozens of relatives including Tempel's mother, that she had missed a deadline to claim a stake in the property, and she then went to Vienna prosecutors.
The Vienna court ruled that Templ illegally omitted the 84-year-old Kretschmer to boost his mother's share of the property.
Templ, who had been estranged from his aunt for 30 years, argued that not mentioning her was a mere oversight. No other claimants mentioned other potential heirs in the paperwork, according to Templ, but he was the only one charged with fraud.
Austria, which came to terms with its Nazi past much later than Germany, has had a complicated history in returning looted property to original Jewish owners and their heirs.
TROUBLED HISTORY OF RESTITUTION CLAIMS
After years of wrangling that reached the U.S. Supreme Court, an arbitration board in 2006 forced Austria's National Gallery to return five paintings by Gustav Klimt to Maria Altmann, the heiress of a Jewish family that had its art stolen.
The more recent discovery in Munich and Salzburg of a billion-dollar art hoard, much of it believed to have been looted or extorted by the Nazis, has reignited a debate over how Austria and Germany have dealt with restitution claims.
Templ, who co-wrote a book in 2001 listing Jewish properties looted by Austrian Nazis and never returned, alleged Austria singled him out for punishment due to his outspoken criticism.
"The whole court ruling is absurd. But even more absurd is the punishment for the whole thing," Templ said by telephone.
"What I am appealing now is just the length and the conditions of the punishment. I can't appeal any more against this stupid or un-understandable court ruling....I can just appeal again in the European Court of Human Rights," he said.
Templ, due to appear in court next week to challenge his sentence, learned in 2005 that the clinic confiscated by Nazi rulers from distant relative Lothar Fuerth would be returned to nine of his heirs.
He travelled to Vienna and - discovering that his mother, 80-year-old Holocaust survivor Helene Templ, was also an heir - filed a claim on her behalf. In 2009, a state panel returned the building to 39 relatives of Fuerth, including Templ's mother, and they later sold it, sharing the proceeds.
Templ was found guilty of defrauding Austria of the stake which the state could have acquired had the aunt given up her portion. Austria's Supreme Court rejected his appeal this year.
He said it was not his responsibility to name all other heirs to the building, and that Austria was aware of his aunt and other potential claimants before the property was returned.
Vienna prosecutors declined to comment on the case. (Editing by Mark Heinrich)