The fall of Colonel Gaddafi's regime in Libya earlier this year gave exiled Jew David Gerbi hope that he could restore lost traces of Jewish life in the country.
But according to Dr Gerbi, when he went back to the country of his birth last week to clean the long disused Tripoli synagogue, armed guards threw him out. He was also told by residents that it was not safe for him to remain in the area.
Reuters reported that he was stopped from entering the synagogue building by guards with rifles.
Dr Gerbi, a psychotherapist, escaped Libya for Italy when he was 12 as anti-Israel feeling rose in the wake of the Six Day War.
He said that he was told by people near the synagogue that if he continued with his efforts he would be killed. Dr Gerbi called on Libya's new leadership, the National Transitional Council, to decide whether it wanted Libya to be a "racist country or a free country".
"The door has been closed again," he said. "But I will not give up."
When Gaddaficame to power an estimated 38,000 Libyan Jews were forced to abandon their homes and livelihoods. Dr Gerbi, who has attempted to build links with the NTC, is a leading figure in the fight to restore property to its former owners.