Arab mediators are scrambling to save the Gaza ceasefire as the Israeli military bolsters troop and tank deployments to the strip’s periphery in advance of the possibility the truce breaks down this weekend.

A Hamas delegation arrived in Cairo on Wednesday to “discuss ways to end the current crisis”, the Palestinian militant group said. Meanwhile, Egyptian and Qatari mediators were working “intensively” to compel Israel to address Hamas’s new demands before Saturday’s scheduled release of three Israeli hostages, Egypt’s state-run al-Qahera television reported.

Mahmoud Mardawi, a senior Hamas official, said there were “positive signals” that the hostage handover would go ahead as planned, but added it had “yet to receive Israel’s commitment to implement the full terms of the deal, especially the humanitarian protocol”. There was no immediate comment from Israeli authorities.

The future of the three-week-old ceasefire agreement was thrown into jeopardy on Monday when Hamas’s armed wing announced it would postpone freeing the next group of captives. It citied alleged Israeli violations of the truce, including the continued killing of Palestinians, blocks on aid, including tents, and delays in allowing displaced people to return to the north of the strip.

It said it had announced its stance early in order to give mediators enough time to pressure Israel to “comply and compensate for the past weeks” before the scheduled weekend handover.

Israel denies the Hamas allegations, but claimed responsibility for an airstrike in the Rafah area on Wednesday that killed two people who the Israel Defense Forces (IDF) said were flying a drone.

The surprise announcement by the US president, Donald Trump, last week that the US would take over and “develop” the Gaza Strip appeared to be central to the group’s decision, although it did not directly mention it in its statement. Hamas reportedly no longer believes Washington’s guarantees for the ceasefire will hold and it does not think Israel is serious about implementation.

The crisis, however, escalated sharply after Trump responded to Hamas’s delay by threatening “hell is going to break out” unless it released all of the Israeli hostages it was holding on Saturday.

After a lengthy cabinet meeting on Tuesday, Israel’s prime minister, Benjamin Netanyahu, appeared to be keeping the option to continue the ceasefire open and a statement from his office did not explicitly back Trump’s call for “all” 76 of the remaining hostages to be freed this weekend.

His defence minister, Israel Katz, echoed the deliberately ambiguous language on Wednesday, saying: “If Hamas does not release the Israeli hostages by Shabbat, the gates of hell will open on them, just as the US president promised. The new Gaza war will be different in intensity from the one before the ceasefire – and will not end without the defeat of Hamas and the release of all the hostages.”

Hamas’s spokesperson, Hazem Qassem, said on Wednesday that Israel was “evading implementation of several provisions of the ceasefire agreement” and reiterated the group’s stance that hostages could only be released through diplomatic means. “Our position is clear, and we will not accept the language of American and Israeli threats,” he said.

Talks on the second stage of the ceasefire, which is supposed to begin in early March, were due to start last week, but an Israeli team sent by Netanyahu to Qatar lacked a mandate to discuss matters not related to stage one, and returned on Sunday night.

Egyptian and Qatari mediators are now trying to persuade Israel to meet the demands Hamas made on Monday, including “implementing the humanitarian protocol … and beginning negotiations for the second phase”, a Palestinian diplomatic source told Agence-France Presse.

The head of the UN, António Guterres, has urged Hamas to proceed with the planned release and “avoid at all costs resumption of hostilities in Gaza”.

The first stage of the truce, in which Israeli captives are released in batches in exchange for Palestinians in Israeli custody, has come under increasing strain as both sides accuse the other of violations.

Last week’s release of three emaciated hostages sparked anger in Israel and beyond. The Gaza health ministry says Israeli fire has killed at least 92 Palestinians and wounded more than 800 others since the fragile ceasefire took hold on 19 January. The IDF says it has fired on people who approach its forces or enter certain areas in alleged violation of the truce.

Trump has doubled down on his proposal to build a “riviera of the Middle East” in Gaza and to relocate its population of 2.3 million people to Egypt and Jordan, a plan international law experts say amounts to ethnic cleansing.

The Arab world has flatly rejected the idea, which could destabilise the region and put Israel’s peace treaties with Egypt and Jordan at risk.

Jordan’s King Abdullah met Trump at the White House on Tuesday, saying in social media posts he “reiterated Jordan’s steadfast position against the displacement of Palestinians”.

Egypt said on Wednesday that it planned to present an alternative vision backed by Arab states for reconstruction of the Palestinian territory that will ensure Gaza’s residents remain on their land.

The ceasefire halted 15 months of fighting in the strip, during which about 48,000 Palestinians were killed, sparking a devastating humanitarian crisis and reducing the occupied territory to ruins. The war was triggered by Hamas’s 7 October 2023 attack on Israel, in which about 1,200 were killed and another 250 taken hostage.