One of the main questions raised during a meeting between President Biden and Vice President Harris with their national security team on Monday was whether Hamas would agree to a hostage release deal and a ceasefire in Gaza, US officials said, according to a report published by the American website Axios on Thursday.

"Biden and his top advisers were shocked after Hamas killed six hostages, including US citizen Hersh Goldberg Polin, and began to rethink the way forward in negotiations on the deal," the site says.

At the same time, US officials said Hamas's new demand to increase the number of Palestinian prisoners released as part of the deal has raised further concerns and questions among US negotiators about whether an agreement is possible.

“We still believe that the deal is the only way to save the lives of the hostages and stop the war,” a US official said. “But the executions not only increased our sense of urgency, but also raised questions about Hamas’s willingness to make any kind of deal.”

According to the website, "American officials said that one of the main arguments made at the meeting was that after Hamas killed the hostages, including an American, the United States should not push for a proposal that would grant Hamas additional concessions, but should instead focus on applying more pressure and accountability measures against Hamas."

One concern raised at the Situation Room meeting was that the United States might pressure Israel to reduce IDF forces deployed along the Egypt-Gaza border or on other issues, only to find that Hamas disagrees with other parts of the deal. That could mean the new offer would simply become the basis for future negotiations that would be more favorable to Hamas, a U.S. official said.

One of the American officials added that during the Situation Room meeting, Biden was briefed on the Justice Department's plan to publish indictments against Hamas leaders, which have been closed since last February.

Hamas officials continued on Wednesday to stress that the United States, Qatar and Egypt need to pressure Israel to agree to their demands.

The site says, “Among the reasons that prompted the publication of this news: White House National Security Adviser Jake Sullivan informed the families of the American hostages on Sunday that Biden is considering presenting an updated and final proposal for the release of the hostages and a ceasefire this week and asked Israel and Hamas to respond.

But in recent days, the White House has appeared less enthusiastic about the option. Biden’s advisers are still in talks with Qatar and Egypt about the updated proposal, but U.S. officials say they don’t want to speculate on a timeline for its presentation.

“The text is basically done, except for two paragraphs, the prisoner exchange annexes and two maps of the IDF deployment in Gaza during the first phase of the deal,” a US official said. “We all feel the urgency, but what happened last weekend changed the nature of the discussion. But we want to try to come up with something.”

According to the American official, the two main points of contention are the issue of control over the Philadelphi Corridor along the border between Egypt and Gaza and the number and identity of Palestinian prisoners that Hamas wants to release during the first phase of the deal.

While the focus in recent weeks has been on the Philadelphia corridor, the prisoner issue has proven equally difficult to resolve, the US official said.

US and Israeli officials said Hamas backed down from its previous positions during negotiations in Doha last week and demanded an increase in the number of prisoners to be released. Many of the prisoners are serving life sentences in Israeli jails for killing Israelis.

The website claims that in previous rounds of negotiations there was an understanding that the first stage of the deal would include the release of 150 Palestinian prisoners serving life sentences, and now Hamas is demanding a larger number, officials said.

"We had a very frustrating process on this in Doha last week," a US official said. "Hamas made different demands than what had been agreed upon in the past."

US officials insist they are still trying to find a solution to the Philadelphia Corridor that can work for both sides.

The draft agreement says that Israeli military forces need to redeploy outside densely populated areas of Gaza during the first phase of the agreement. The US official said the argument is to identify areas that are considered densely populated along the 14-kilometer (9-mile) road along the Egypt-Gaza border, according to the website.

The official said the United States believes the map presented by Israel is consistent with the principles of the deal because it included a significant reduction in the number of troops and their deployment outside densely populated areas.

At the same time, the official suggested that Israel could make additional "adjustments" to the IDF's deployment in the area in order to allow for an agreement.

“The Philadelphi corridor has become a political issue… I have seen some Israeli ministers claim that the agreement endangers Israel’s security. That is not true. Not accepting the agreement poses a greater risk to Israel’s security than accepting the agreement, including when it comes to Philadelphia,” the US official said.

US officials say they believe that even if the Philadelphi Corridor issue is resolved somehow, Hamas will still insist on releasing more prisoners, the website reported.