A senior Israeli negotiator told AFP Monday that tens of hostages held by Hamas in Gaza are certainly alive and that Israel cannot accept halting the war until all captives are released in a deal.
Hamas militants seized 251 hostages on 7 October, of whom Israel believes 116 remain in Gaza, including 41 who the army says are dead.
"Tens are alive with certainty," the official said on condition of anonymity as he was not authorised to speak publicly on the issue.
"We cannot leave them there a long time, they will die," he said, adding that a vast majority of them were being held by Hamas militants.
US President Joe Biden last month unveiled a three-phase proposal to end the war in Gaza, which includes a ceasefire and the release of hostages held by Hamas.
Biden said the first phase includes a "full and complete ceasefire" lasting six weeks, with Israeli forces withdrawing from "all populated areas of Gaza".
The official said Israel could not end the conflict with Hamas before a hostage deal because the militants could "breach their commitment... and drag out the negotiations for 10 years" or more.
"We cannot, at this point in time - before signing the agreement - commit to ending the war," the official said.
"Because during the first phase, there's a clause that we hold negotiations about the second phase. The second phase is the release of the men and male soldier hostages."
The official said the Israeli negotiating team had greenlit the Biden plan.
"We expect, and are waiting for, Hamas to say 'yes,'" the official said.
The Israeli government has yet to publicly approve the Biden plan.
"In the event we don't reach an agreement with Hamas, the IDF (army) will continue to fight in the Gaza Strip in a no less intense fashion than it's fighting now," he said.
"In a different manner, but an intense manner."
The war between Israel and Hamas broke out after Hamas carried out an attack on Israel on 7 October that resulted in the deaths of 1,194 people, mostly civilians, according to an AFP tally based on official Israeli figures.
Israel's retaliatory campaign in Gaza has killed at least 37,347 people, also mostly civilians, with a further 85,372 wounded and leaving the enclave on the brink of famine.