Gulf states Saudi Arabia, the UAE and Qatar all condemned on Tuesday the Israeli parliament's decision to ban the UN agency for Palestinian refugees, UNRWA, from operating in Israel.
Israel's parliament on Monday overwhelmingly voted to ban UNRWA from working in Israel and occupied east Jerusalem.
The lawmakers also passed a measure prohibiting Israeli officials from working with UNRWA and its employees.
Gulf emirate Qatar, a mediator in negotiations over the Gaza war between Israel and Hamas, warned of disaster.
"We emphasise that stopping support for UNRWA will have disastrous consequences," foreign ministry spokesman Majed al-Ansari told reporters in Doha.
"The international community cannot stand silent in the face of this disregard for its international institutions," he added.
Qatar, along with the United States and Egypt, has mediated months of negotiations for a deal to end the war on Gaza and exchange Israeli captives held in the territory for Palestinian prisoners held by Israel.
Saudi Arabia's foreign ministry in a statement also denounced the Israeli decision, calling it "a flagrant violation of international law".
It said the move "contravenes international legitimacy" amid the "indescribable humanitarian catastrophe" for Palestinians in Gaza.
The United Arab Emirates foreign ministry, in a post on X, "strongly condemned" the new Israeli law.
The UAE said the ban contravenes the UN charter "and will exacerbate the critical and deteriorating humanitarian situation".
Talks on the Gaza war have so far failed to bring an agreement, with each warring party accusing the other of blocking it.
Renewed talks
In a bid to break the deadlock, Washington and Doha last week announced a fresh round of in-person talks in Doha that would explore new options.
With the US presidential election around the corner, Ansari told reporters that Qatar did not see "any negative result of the elections on the mediation process itself".
He added that Qatar believes it is "dealing with institutions and in a country like the United States, the institutions are invested in finding a resolution to this crisis".
UNRWA has provided essential aid, schooling and healthcare across the Palestinian territories and to Palestinian refugees elsewhere for more than seven decades.
It and other humanitarian agencies have accused Israeli authorities of restricting aid flows into Gaza, where almost all of the territory's 2.4 million people have been displaced at least once during the war.
The agency itself has suffered heavy losses, with at least 223 of its staff killed by Israeli forces and two-thirds of its facilities in Gaza damaged or destroyed since the war on the Strip began.