Families of hostages held in Gaza called on Monday for an investigation into the leak of secret documents by a former aide to the prime minister, which could undermine efforts to return the captives in the blockaded territory.

An Israeli court said on Sunday that Eliezer Feldstein was arrested along with three other people, including members of security services, on charges of leaking documents to foreign media.

The case prompted the opposition to question whether Netanyahu was involved in the leaks, which the Prime Minister's Office denied, according to Agence France-Presse.

"The families of the hostages demand that all suspects of sabotage and undermining state security be investigated," the Israeli Forum of Hostages and Missing Persons said in a statement.

He added: "Such actions, especially during war, put the hostages at risk, threaten their chances of return, and leave them at risk of being killed by Hamas terrorists."

The forum represents most of the families of the 97 hostages still being held in the Gaza Strip, 34 of whom the military says are dead.

According to the forum, “there are suspicions that individuals linked to the prime minister acted to carry out one of the largest frauds in the country’s history.”

The forum considered that "this is an act that reflects moral degradation, and it is a severe blow to the remaining trust between the government and its citizens."

Netanyahu's critics have long accused him of stalling on a truce and prolonging the war to please his far-right coalition partners.

The Shin Bet domestic intelligence agency and the military opened an investigation into the leaks in September, after the Jewish Chronicle in London and the German newspaper Bild published reports based on secret military documents.

One of the reports claimed to have uncovered a document showing that Hamas leader Yahya Sinwar, who was later killed by Israel, and the hostages in Gaza would be smuggled out of the Strip into Egypt via the Philadelphi Corridor on the Gaza-Egypt border.

The second report was based on what was said to be an internal memo from the Hamas leadership regarding Sinwar’s strategy to obstruct negotiations for the release of the hostages.

The first leaked document turned out to be forged, while the internal memo was actually drafted by Hamas activists who do not hold senior positions, according to Israeli press reports.

The Israeli court said that publishing the documents would likely cause "serious harm to state security."

She added, "As a result, it was possible to undermine the ability of the security services to free the hostages, as part of the war's objectives."

Hamas still holds 97 hostages in the Gaza Strip and the army says 34 of them are dead (AFP)

Israel vowed to "eliminate" Hamas after its attack on the Jewish state, which killed 1,206 people, most of them civilians, according to a count by Agence France-Presse, based on official data. 251 people were also kidnapped during the attack.

Since then, Israel has been waging a campaign of concentrated bombing and ground operations in the Gaza Strip, killing at least 43,341 Palestinians, most of them women and children, according to the latest data from the Hamas-run Health Ministry, which the United Nations considers reliable.