Prime Minister Benjamin Netanyahu issued a rare apology to the families of the six executed hostages but insisted that he would not cave on the issue of retaining a military force in the Philadelphi Corridor.

"My heart and the heart of the nation is shattered into pieces," Netanyahu said in a special press conference in which he defended his unwavering stance in the face of criticism that he was thwarting a deal.

He spoke as the death of the hostages shot at close range by their captors over the week rocked the nation, with the country's largest union holding a national strike demanding an immediate deal.

To the families of the six hostages, he said, "I ask for your forgiveness that we did not succeed in bringing them home alive. We were close, but we did not make it."

Netanyahu stressed, "I am working around the clock, looking for every path possible" to bring the remaining 101 hostages back to Israel.

"I have insisted on the return of the maximal number of live hostages," he said, as he explained that at present he has brought that number up to 23 in the first phase, it's estimated that some 66 captives are still alive.

Earlier in the day, US President Joe Biden blamed both Netanyahu and Hamas for the absence of a deal.

Biden spoke with reporters prior to his meeting with members of his negotiating team at the White House on Monday, after hearing that one of the six captives was Israeli-American Hersh Goldberg-Polin, 23.

He appeared to confirm reports that the US would soon present a final hostage deal to Israel and Hamas.

"We're very close to that," he said when asked about that report. He was also quizzed as to why this effort would be successful when past initiatives had failed."Hope springs eternal," Biden said in response, adding "We're not giving up. We're going to continue to push as hard as we can."