Russia and China, which hold veto powers in the U.N. Security Council, raised concerns on Thursday with a U.S. draft resolution that would back a proposal - outlined by President Joe Biden - for a cease-fire between Israel and Palestinian militants 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 U.S., France, Britain, China or Russia to pass.

Biden laid out a three-phase cease-fire plan for the Gaza Strip a week ago that he described as an Israeli initiative.

The U.S. is seeking international support for the plan that Hamas is still studying. It circulated a one-page draft resolution to the 15-member U.N Security Council on Monday and a revised version on Wednesday, both seen by Reuters.

The current draft welcomes the cease-fire 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 cease-fire" 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 cease-fire and unconditional release of all hostages, diplomats said.

Russia proposed amendments to the U.S. 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 cease-fire respected by all parties.

Moscow also wants the draft to stress that the phase one cease-fire will remain in place as long as negotiations continue on phase two, reflecting remarks made by Biden last week.

For months, negotiators from the U.S., Egypt and Qatar have been trying to mediate a cease-fire. 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 militants.

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.

Israel launched an air, ground and sea assault on the blockaded Palestinian territory, killing more than 36,000 Palestinians, according to Gaza health authorities.