Palestinian leaders are lobbying desperately against the relocation of Israel’s US embassy from Tel Aviv to Jerusalem, with Arab League chief Ahmed Abul Gheit saying such a move would boost fanaticism and violence while sinking hopes for peace.
He said his organisation was closely following the issue and is in contact with the Palestinian authorities and Arab states to co-ordinate the Arab position if US president Donald Trump takes the step.
"It is unfortunate that some are insisting on carrying out this step without any regard to the dangers it carries to the stability of the Middle East and the whole world," he told reporters in Cairo on Sunday.
"Nothing justifies this act … it will not serve peace or stability, instead it will nourish fanaticism and violence.”
Palestinians have been lobbying regional leaders to oppose the decision and the armed Islamist movement Hamas has threatened to launch a new "intifada".
Jared Kushner, Mr Trump’s son-in-law and senior adviser, made a rare public appearance on Sunday and did not deny reports that Mr Trump will declare Jerusalem Israel’s capital on Wednesday.
"The president's going to make his decision," Mr Kushner told the Saban Forum.
"He's still looking at a lot of different facts and when he makes his decision he'll be the one who wants to tell you. So he'll make sure he does that at the right time."
Mr Trump must on Monday decide whether to sign a legal waiver that would delay plans to move the embassy from Tel Aviv to Jerusalem for another six months — something that every US president has done since 1995.
Palestinian president Mahmud Abbas spoke to Hamas leader Ismail Haniya late on Sunday, a Hamas statement said, with the two sides agreeing their opposition to any shift in US policy.
The rare call between the two comes as attempts at implementing a reconciliation deal have faltered in recent days.
Meanwhile, the Palestinian foreign ministry called for an emergency meeting between the Arab League and Organisation of Islamic Cooperation (OIC) to discuss the possible “irresponsible” US action and “necessary steps” if Mr Trump declared Jerusalem the capital of Israel.
Saeb Erekat, secretary general of the Palestine Liberation Organisation, warned a change in the US stance on Jerusalem would spell disaster.
In a statement, he warned the US would "be disqualifying itself to play any role in any initiative towards achieving a just and lasting peace”.
Jordan's foreign minister Ayman Safadi also warned against the dangers of recognising Jerusalem as Israel's capital in a phone call with US secretary of state Rex Tillerson on Sunday night, reported Jordan's state-run Petra news agency.
"He insisted [during the phone call] on the need to maintain the historical and legal situation of Jerusalem and on not taking any decision that might change that," said the report.
"He warned of the dangers, as Jerusalem is not only holy to Palestinians and Jordanians but to the whole Arab Muslim world.
"It will negatively affect US efforts to establish Palestinian-Israeli peace, efforts that Jordan has welcomed and Arab countries support."