The Palestinians will freeze their ties with the US if it follows through on a threat to close the Palestine Liberation Organisation's office in Washington, a senior PLO official warned Saturday.
The surprise American move and Palestinian backlash came as US President Donald Trump seeks bargaining chips in his bid to broker an elusive Israeli-Palestinian peace deal.
Trump has a 90-day window to avert the closure if he deems progress has been made.
But PLO Secretary General Saeb Erekat said his organisation had officially informed Washington that "we would put on hold all our communications with this American administration" if the office were closed.
The PLO, which the international community sees as representing all Palestinians, must have its permission to operate its premises in the American capital renewed every six months.
Palestinian foreign minister Riyad al-Malki said it was the first time since the 1980s that the State Department had refused to renew it.
Malki told AFP Palestinian officials had received a letter from Washington two days ago "saying that the Secretary of State had not found enough reasons to keep the office open".
"This has not happened in the past, and we have demanded clarifications from the State Department and the White House," he said.
"They told us that there would be a meeting of senior legal experts on Monday. Then they would give a clear answer," he said, adding that Palestinian leaders would then meet to discuss their response.
A US State Department official cited "certain statements made by Palestinian leaders" about the International Criminal Court as the reason behind the non-renewal.
Palestinian president Mahmud Abbas, in his latest speech at the UN General Assembly, suggested taking the issue of Israeli settlements to the ICC.
In 2015 Congress issued a resolution barring Palestinians from seeking to wield influence over the ICC regarding investigations into Israeli nationals.
- Abbas 'deeply surprised' -
Palestinian president Mahmud Abbas was "deeply surprised" by the State Department's move, his spokesman Nabil Abu Rudeina said in remarks carried by official Palestinian news agency WAFA on Saturday.
He said the decision "represents an unprecedented step in the history of the Palestinian-American relationship, and has dangerous consequences for the peace process and the American-Arab relations."
It "represents a blow to attempt to build peace", he said.
The State Department official said Trump had 90 days to decide whether to waiver the decision if he deems "the Palestinians have entered into direct, meaningful negotiations with Israel".
The peace process has been deadlocked since April 2014 following the collapse of indirect negotiations led by then US secretary of state John Kerry.
The State Department official said Washington was hopeful any "closure will be short-lived," emphasising that "we are not cutting off relations with the PLO, nor do we intend to stop working with the Palestinian Authority."
"This measure should in no way be seen as a signal that the US is backing off those efforts."
The office of Israeli Prime Minister Benjamin Netanyahu said the decision was "a matter of US law."
"We respect the decision and look forward to continuing to work with the US to advance peace and security in the region," his office said.
In a video on Twitter, Erekat called the decision "very unfortunate and unacceptable", blaming it on pressure exerted by Netanyahu's government.
"At a time when we are trying to cooperate to achieve the ultimate deal they take such steps which will undermine the whole peace process," Erekat said, echoing Trump's pledges to forge an Israeli-Palestinian peace agreement.