Russia has laid the groundwork for a likely veto on Monday of a British, U.S. and French bid for the United Nations Security Council to call out Iran over its weapons falling into the hands of Yemen's Houthi group.
The 15-member Security Council has to renew its targeted sanctions on Yemen on Monday.
Russia has proposed a rival resolution that would simply extend the mandate of the regime for one year and not mention Iran.
The United States has been lobbying for months for Iran to be held accountable at the United Nations, while at the same time threatening to quit a 2015 deal among world powers to curb Iran's nuclear program if "disastrous flaws" are not fixed.
Britain drafted a resolution in consultation with the United States and France that initially wanted to condemn Iran for violating an arms embargo on Houthi leaders and include a council commitment to take action over it.
The latest British draft drops the condemnation and instead expresses concern that U.N. experts monitoring the sanctions reported Iran had violated a targeted arms embargo by failing to stop missiles and unmanned aerial vehicles reaching the Houthis.
A proxy war is playing out in Yemen between Iran and U.S. ally Saudi Arabia.
A Saudi-led coalition intervened in Yemen in 2015, backing government forces fighting Iran-allied Houthi rebels. Iran has denied supplying the Houthis weapons.
A U.N. Security Council resolution needs nine votes in favor and no vetoes by Russia, China, the United States, France or Britain to pass.
Both resolutions seek to renew a U.N. ban on the supply of weapons to Houthi leaders and "those acting on their behalf or at their direction." It can also blacklist individuals and entities for threatening the peace and stability of Yemen or hindering aid access.
U.S. Ambassador to the United Nations Nikki Haley took her Security Council colleagues to Washington in January to view pieces of missiles fired by the Houthis at Saudi Arabia in a bid to boost the U.S. case against Iran.
Russian U.N. Ambassador Vassily Nebenzia said after the visit that he does not believe there is a case for United Nations action against Iran. Iran has described the arms displayed in Washington as "fabricated."