Israel said it has begun preparations for the departure of large numbers of Palestinians from the Gaza Strip in line with President Donald Trump’s plan for the territory.
Officials meanwhile said Egypt has launched an diplomatic blitz behind the scenes to try and head off the plan.
The Trump administration has already dialled back aspects of the proposal after it was widely rejected internationally, saying the relocation of Palestinians would be temporary.
US officials have provided few details about how or when the plan would be carried out.
The Palestinians have vehemently rejected Mr Trump’s proposal, fearing Israel will never allow the refugees to return and that it would destabilise the region.
Egypt has warned that such a plan could undermine its peace treaty with Israel, a cornerstone of stability and American influence in the Middle East for decades.
Saudi Arabia, another key US ally, has also rejected any mass transfer of Palestinians and says it will not normalise relations with Israel — a key goal of the Trump administration — without the creation of a Palestinian state that includes Gaza.
Mr Trump and Israeli officials have depicted the proposed relocation from war-ravaged Gaza as voluntary, but the Palestinians have universally expressed their determination to remain in their homeland.
Mr Trump and Israeli officials have not said how they would respond if Palestinians refuse to leave.
But Human Rights Watch and other groups say the plan, if implemented, would amount to “ethnic cleansing”, the forcible relocation of the civilian population of an ethnic group from a geographic area.
Israeli Defence Minister Israel Katz said he has ordered the military to make preparations to facilitate the emigration of large numbers of Palestinians from Gaza through land crossings as well as “special arrangements for exit by sea and air”.
There were no immediate signs of such preparations on the ground.
Egyptian President Abdel-Fattah el-Sissi has not publicly responded to Mr Trump’s stunning proposal that most of Gaza’s population of 2.3 million Palestinians be relocated and the United States take charge of rebuilding the territory.
Israel’s 15-month campaign against the militant Hamas group had reduced large parts of Gaza to rubble before a fragile ceasefire took hold last month.
But Egyptian officials said Cairo has made clear to the Trump administration and Israel that it will resist any such proposal, and that the peace deal with Israel — which has stood for nearly half a century — is at risk.
One official said the message has been delivered to the Pentagon, the State Department and members of the US Congress. A second official said it has also been conveyed to Israel and its Western European allies.
Mr Trump said he wanted to “permanently” resettle most of Gaza’s population in other countries and for the United States to take charge of clearing debris and rebuilding Gaza as a “Riviera of the Middle East” for all people.
He did not rule out the deployment of US troops there.
US officials later appeared to walk it back, saying the relocation of Palestinians would be temporary and that Mr Trump had not committed to putting American boots on the ground or spending American tax dollars in Gaza.
The Egyptian officials said their government does not believe the Palestinians need to be relocated for reconstruction to proceed and is committed to the creation of a Palestinian state in Gaza, the West Bank and east Jerusalem, territories Israel seized in the 1967 Mideast war.
Israel’s government is opposed to Palestinian statehood and has said it will maintain open-ended security control over both Gaza and the occupied West Bank.
Israel annexed east Jerusalem in a move not recognised by most of the international community and considers the entire city its capital.