Negotiators from multiple countries met in Cairo on Tuesday, struggling to reach an agreement to temporarily stop the war in the Gaza Strip as international concern mounted over Israel’s plan to press its ground offensive into the city of Rafah, where more than half of the territory’s population has sought refuge.

Talks involving lower-level officials will continue for another three days, according to an Egyptian and an American official briefed on the matter, who spoke on condition of anonymity to discuss sensitive diplomacy. They described the negotiations Tuesday as promising, but Israel and Hamas were still not close to a deal.

A primary obstacle, according to another U.S. official, is a disagreement on how many Palestinians Israel would release from its prisons in exchange for the release of hostages held in Gaza by Hamas and its allies. A series of exchanges in late November saw three Palestinians released for each hostage returned.

President Joe Biden sent the CIA director, William Burns, to join the talks, and said that he had spoken with Prime Minister Benjamin Netanyahu of Israel and the leaders of Egypt and Qatar to “push this forward” over the past month. Officials of Hamas, the armed group fighting Israel, were taking part in the negotiations indirectly, using Qatar and Egypt as intermediaries.

The talks came as the United Nations, the United States and other countries have expressed increasing alarm about the prospect of an Israeli incursion into Rafah on the southern edge of Gaza, where about 1.4 million people are sheltering, many in tents, without adequate food, water and medicine.

Netanyahu has said that Israel will conduct such an offensive and has ordered the military to draw up plans to evacuate civilians from the city. But many Palestinians and international aid groups say that no place in Gaza is safe and that moving people away from Rafah, the main entry point for vital aid, will worsen their lot.

Biden said Monday that the United States opposes an Israeli invasion of the city without a “credible plan” to protect civilians from harm. Egypt has said it will not let refugees cross the border into Sinai.

John Kirby, a National Security Council spokesperson, said Tuesday that the talks were “moving in the right direction” but declined to provide details.

“Nothing is done until it is all done,” he told reporters at the White House.Negotiators in Cairo, Biden said, were hoping to hammer out an agreement that would free the remaining hostages in Gaza and halt the fighting for at least six weeks. Burns was meeting with the head of Mossad, Israel’s intelligence agency, as well as the prime minister of Qatar and Egyptian officials, according to Al Qahera, an Egyptian state-owned television channel.

Hamas officials have said they will only release the remaining hostages in Gaza, believed to number more than 100, if Israel abides by a long-term cease-fire, withdraws from Gaza and releases Palestinians being held in Israeli jails.

Netanyahu has said that Israeli troops will not stop fighting in Gaza until the hostages are freed and Hamas is crushed. Even then, he has said, Israeli forces must be responsible for security in Gaza, casting doubt on the idea of a withdrawal. But his government has also been facing pressure from relatives of the hostages to make a deal.

“Do not return until everyone comes home — the living and the dead,” the Hostages and Missing Persons Families Forum, a group representing relatives of the captives, said Tuesday, in a direct appeal to Israeli officials who were in Cairo for the talks. “The eyes of 134 hostages are upon you.”

The expected Israeli advance into Rafah has led to intense pressure on Egypt, which shares a border with Gaza that has only one crossing point for goods and people, at Rafah. Rather than opening its gates to give Palestinians a refuge from the expected onslaught, Egypt has reinforced its frontier with Gaza.

Egyptian officials have been quoted as saying that any action that sends Palestinians spilling into Egyptian territory could jeopardize the decades-old peace treaty between Israel and Egypt, an anchor of stability in the Middle East. But on Monday, Egypt offered assurances that the treaty would stand.

Many Palestinians say that Israel wants to expel them, and they fear that if they ever left, Israel would not allow them back in — just as Arabs who fled or were expelled from Israel at its formation have not been permitted to return.

Netanyahu, vowing to crush Hamas, has described Rafah as its last stronghold in Gaza. Securing the city, he has said, is critical to preventing another attack like the one on Oct. 7, when militants led by Hamas killed about 1,200 people in Israel and abducted more than 250 others, according to Israeli officials.

On Monday, after Israeli commandos freed two of the hostages held in Rafah, Netanyahu said that “only continued military pressure, until total victory, will bring about the release of all of our hostages.”

Harel Chorev, a researcher at Tel Aviv University, said the rescue could be used to strengthen Netanyahu’s argument for an expanded ground invasion.

“It shows that military pressure works, and that at the end of the day, it can justify Israel’s position regarding the necessity to go into Rafah,” Chorev said.

But Ibrahim Dalalsha, the director of Horizon Center for Political Studies and Media Outreach in the Israeli-occupied West Bank, said the high Palestinian death toll from the raid could spur Egypt, the U.S. and Qatar to push harder for a deal.

At least 67 people were killed in Israeli attacks that accompanied the rescue operation, according to the Gaza Health Ministry. More than 28,000 people in Gaza have been killed in Israel’s military campaign, the health ministry says.

“They want to avoid further operations like these with their human casualties and the possibility of the hostages being killed,” Dalalsha said.

Since Oct. 7, Israel has conducted an intense aerial bombardment and ground invasion, concentrated at first in northern Gaza and then working its way southward. It has repeatedly told civilians to evacuate, displacing many of them multiple times and squeezing them steadily into a smaller space and more squalid conditions. Rafah has been the last area remaining where it told Palestinians to take refuge — and even it has not been immune to airstrikes.

South Africa said Tuesday that it had asked the International Court of Justice to consider whether a full-scale invasion of Rafah would violate an interim ruling that the court issued last month, when it called on Israel to take steps to prevent acts of genocide by its forces in Gaza.

South Africa, which brought the case accusing Israel of genocide, said that Israel’s plan to expand its ground offensive in Rafah “has already led to and will result in further large-scale killing, harm and destruction.”

Israel’s foreign ministry did not immediately respond to a request for comment Tuesday, but Israel has strongly rejected accusations of genocide. Last month, the court did not rule on whether Israel was committing genocide, and it did not call on Israel to stop its military campaign to eliminate Hamas.

The New York Times New Service