A nationwide strike aimed at ramping up pressure on Israel's government to secure the release of the remaining hostages in Gaza was set to begin Monday.

The call by Israel's largest union to paralyse the economy follows a night of massive demonstrations, with tens of thousands of protesters taking to the streets in an outpouring of grief and fury over six hostages killed in the Gaza Strip, reports AFP.

Relatives and demonstrators accused the government of not doing enough to bring them back alive, and called for an immediate ceasefire to rescue the dozens still captive.

"We must stop the abandonment of the hostages... I have come to the conclusion that only our intervention can shake those who need to be shaken," said Histadrut union chair Arnon Bar-David.

"Starting today (Monday) at six in the morning, the entire Israeli economy will go on complete strike."

Of the 251 hostages seized during Hamas's October 7 attack on Israel, 97 remain captive in Gaza, including 33 the army says are dead.

Scores were released during a one-week truce in November, with campaigners and family members believing another deal is the best option to ensure the rest return.

"We are asking our government to stop everything and to make a deal," Yair Keshet, uncle of hostage Yarden Bibas, said during Sunday night's protest in Tel Aviv.

Critics have accused Prime Minister Benjamin Netanyahu of prolonging the war for political gain.

"Were it not for the delays, sabotage and excuses" in months of mediation efforts, the six hostages "would likely still be alive", campaign group the Hostages and Missing Families Forum said in a statement.

Bd pratidin English/Lutful Hoque