Russia and China, which hold veto powers in the UN Security Council, raised concerns on Thursday with a US draft resolution that would back a proposal - outlined by President Joe Biden - for a ceasefire between Israel and Hamas.
The council's only Arab member, Algeria, also signaled it was not ready to back the text, diplomats said. A resolution needs at least nine votes in favor and no vetoes by the US, France, Britain, China or Russia to pass.
Biden laid out a three-phase ceasefire plan for the Gaza Strip a week ago that he described as an Israeli initiative.
The US is seeking international support for the plan that Hamas is still studying. It circulated a one-page draft resolution to the 15-member UN Security Council on Monday and a revised version on Wednesday, both seen by Reuters.
The current draft welcomes the ceasefire proposal, describes it as "acceptable" to Israel, "calls upon Hamas to also accept it, and urges both parties to fully implement its terms without delay and without condition."
It lists some details of the proposal - with "a full and complete ceasefire" in the Gaza Strip as part of phase one and "upon agreement of the parties, a permanent end to hostilities" in phase two.
But some council members have raised questions about whether Israel has actually accepted the plan and want the council to stick to a demand made in March for an immediate ceasefire and unconditional release of all hostages, diplomats said.
Russia proposed amendments
Russia proposed amendments to the US text, which were seen by Reuters, that included calling upon both Hamas and Israel to accept the proposal and demanding an immediate, unconditional and permanent ceasefire respected by all parties.
Moscow also wants the draft to stress that the phase one ceasefire will remain in place as long as negotiations continue on phase two, reflecting remarks made by Biden last week.
For months, negotiators from the US, Egypt and Qatar have been trying to mediate a ceasefire. Hamas says it wants a permanent end to the war in the Gaza Strip and Israeli withdrawal from the enclave of 2.3 million people.
Israel is retaliating against Hamas, which rules Gaza, over an Oct. 7 attack by its fighters.
More than 1,200 people were killed and over 250 taken hostage by Hamas on Oct. 7, according to Israeli tallies. More than 100 hostages are believed to remain captive in Gaza.