An Israeli group campaigning for the release of captives held in Gaza called on Monday for an investigation into the alleged leak of confidential documents by an ex-aide to the prime minister, which may have undermined efforts to secure the captives' release.
An Israeli court announced on Sunday that Eliezer Feldstein, a former aide to Benjamin Netanyahu, had been detained along with three others for allegedly leaking documents to foreign media.
The case has prompted the opposition to question whether Netanyahu was involved in the leak.
"The families demand an investigation against all those suspected of sabotage and undermining state security," said a statement by the Hostages and Missing Families Forum, which represents most of the families of the 97 hostages.
"The suspicions suggest that individuals associated with the prime minister acted to carry out one of the greatest frauds in the country's history," the forum said.
"This is a moral low point like no other. It is a severe blow to the remaining trust between the government and its citizens."
Critics have long accused Netanyahu of stalling in truce negotiations and prolonging the war to appease his far-right coalition partners.
Israel's domestic security agency Shin Bet and the army launched an investigation into the breach in September after two newspapers, British weekly The Jewish Chronicle and Germany's Bild tabloid, published articles based on the classified military documents.
One claimed a document had been uncovered showing that then Hamas leader Yahya Sinwar - later killed by Israel - and the captives in Gaza would be smuggled out of the territory into Egypt through the Philadelphi corridor along the Gaza-Egypt border.
The other was based on what was said to be an internal memo from the Hamas leadership on Sinwar's strategy to hamper talks towards the liberation of hostages.
The Israeli court said the release of the documents ran the risk of causing "severe harm to state security".
"As a result, the ability of security bodies to achieve the objective of releasing the hostages, as part of the war goals, could have been compromised," it added.
Israel's war on Gaza has so far killed at least 43,341 people, a majority of them civilians, according to the territory's health ministry.