Photographs of some of those taken hostage by Hamas during their recent attacks are seen on October 18, 2023 in Tel Aviv, Israel.
CNN  — 

Talks to secure the release of a large number of hostages being held by Hamas in Gaza are ongoing, two sources familiar with the matter and one western diplomat familiar with the discussions told CNN, but the negotiations are being complicated by a number of factors.

The United States, Israel, Qatar, Egypt and Hamas are engaged in the ongoing deliberations. Four hostages – two American and two Israeli – have been freed so far. But the hope now is to reach a deal for a bigger group of hostages released at once.

Israel is pressing for a comprehensive plan for such a release, another source said, after seeing just two sets of two hostages released so far. Israel has said there are more than 200 hostages believed to be held by Hamas in Gaza.

Israel has so far held off on making a ground incursion into Gaza, and the US has pressed Israel to further delay its invasion to allow for the release of more hostages held by Hamas.

The sources said the timing of the ground invasion is a moving target.

There is no specific timeline to that delay, and the sources said they don’t believe the Israelis will hold off for more than a few days.

As part of the negotiations, Hamas wants more fuel allowed into the coastal enclave, according to a person familiar with the group’s demands, but Israeli officials have made clear publicly that that isn’t negotiable.

A senior adviser to the prime minister, Ambassador Mark Regev, told CNN Monday night: “The government decision is that fuel doesn’t go in because it will be stolen by Hamas and it’ll be used by them to power rockets that are fired into Israel to kill our people.” Regev said that Israel will not allow more fuel into Gaza even if Hamas released all of the hostages.

However, in a speech on Tuesday, the Israel Defense Forces chief of staff said efforts will be made to provide access to fuel in Gaza where needed to alleviate the humanitarian crisis, but that it would “not allow” the fuel to reach Hamas.

“We will make sure there will be fuel in places where they need fuel to treat civilians. We will not allow the fuel for Hamas so they can continue fighting against the citizens of Israel,” Lt. Gen. Herzi Halevi said.

In a telephone call Monday evening, President Joe Biden and Prime Minister Benjamin Netanyahu discussed the situation surrounding the hostages as planning toward a ground invasion proceeds.

“The President welcomed the release of two additional hostages from Gaza earlier today, and reaffirmed his commitment to ongoing efforts to secure the release of all the remaining hostages taken by Hamas – including Americans – and to provide for safe passage for US citizens and other civilians in Gaza,” the White House said after the call.

Determining how to release a larger round of hostages – if it were ultimately agreed upon – has been an extraordinarily complex undertaking. Gaza has been under constant bombardment by Israel since Hamas attacked the country on October 7, and moving a large group when strikes are ongoing would put them in harm’s way.

Nine of the ten unaccounted for Americans are US citizens and one is a permanent resident. US officials are working to find “alternatives” to move the hostage negotiations along, a US official said. “We’re actively working it,” they said.

An additional complicating factor is that the hostages are believed to be – as US officials have previously said – to be located in different areas of Gaza.

On Monday, when asked whether the US would support a “hostages-for-a-ceasefire” deal, Biden said: “We should have a ceasefire.” He quickly amended his answer, saying: “Not a ceasefire, we should have those hostages released, and then we can talk.”

But Israeli officials have been adamant that they will not agree to a ceasefire.

“We are working across all channels to release all hostages. Our goal remains the same and we will achieve it. Dismantling Hamas is no easy task and will take however long it takes,” an official in the Israeli prime minister’s office said.