A parliamentary committee in Israel is to investigate the death of a man reported to have been an Australian immigrant recruit to the Mossad spy agency, in an isolation cell in 2010.
An announcement was issued on Sunday by the foreign affairs and defence committee.
The death of Ben Zygier, 34, was kept under wraps for two years until it was revealed by ABC TV in Australia last Tuesday on the Foreign Correspondent programme.
Zygier is said to be a Mossad operative held on suspicion of security offences. His death was apparently suicide.
Zygier, who immigrated to Israel in around 2001, is understood to have been arrested in February 2010. Ten months later, he was found hanged in his cell despite being under 24-hour surveillance.
The government has restricted reporting in Israel on the case, using court orders, military censorship and direct requests to news editors.
Without citing the case specifically, Prime Minister Benjamin Netanyahu said on Sunday he "absolutely trusts" Israel's security services.
"We are an exemplary democracy," Mr Netanyahu said.
"But we are also more threatened, more challenged, and therefore we have to ensure the proper operation of our security branches.
"Therefore I ask over everyone: Let the security services continue working quietly so that we can continue to live in safety and tranquility in the State of Israel."
Mossad was accused by Dubai in early 2010 of using Australian passport-holders to assassinate a Palestinian arms buyer in a hotel there.
There is speculation that Israel suspected Zygier of betraying or threatening to divulge Mossad missions.
Lawyer Avigdor Feldman said last week that his client had denied "grave charges" for which he awaited trial. He also said that Zygier's family knew about his detention. The incarceration was approved by several Israeli courts.
Intelligence Minister Dan Meridor and Strategic Affairs Minister Moshe Yaalon told Israeli media on Saturday the case was rare but lawful.
Meridor said that publishing the prisoner's identity would have risked "serious harm to security." He did not elaborate.