TUNIS: The family of a murdered Tunisian described by Palestinian Islamist movement Hamas as a long-time member called on the authorities Friday to release details of the investigation into his killing.

Unknown gunmen shot dead engineer Mohamed Zouari with a hail of bullets outside his house in central Tunisia in December 2016.

Hamas, which said the 49-year-old engineer and drone expert had worked with it for a decade, at the time blamed Israel for the killing.

On Thursday, it said Israeli spies had used Bosnian passports to enter Tunisia and assassinate Zouari, who also held Belgian citizenship.

His widow Majda Saleh on Friday slammed the authorities for their "big silence" over his death.

"I want justice to be done for Mohamed Zouari," she told Mosaique FM radio station.

"We are aware that Israel is behind his assassination, but specific parties are also involved," she said. "Who are they?"

"I hope that the Tunisian government will not close (Zouari's) file and that it will resume the investigation," said Saleh, who is Syrian but has applied for Tunisian nationality.

Tunisian authorities were not immediately available for comment.

Zouari's brother Radhouene said authorities appeared to be "counting on time for public opinion to forget this case".

"We have a series of questions... we would like someone at the interior ministry to answer those questions," he told the same radio station.

The government has said "foreign elements" were involved in Zouari's killing in Tunisia's second city Sfax last December 15.

Israel has previously faced criticism after its agents reportedly used British, Irish, Australian and other passports to assassinate a Hamas leader in the United Arab Emirates in 2010.