Chinese Foreign Ministry spokesman Kong Quan said the Russian plan, proposed earlier this week when Iran's chief nuclear negotiator visited Moscow, "could be helpful to break the stalemate."
Kong's remarks came as Iran's High Council of National Security Secretary Ali Larijani met with Chinese officials in Beijing in an apparent bid by Tehran to strengthen support with another of its key allies.
"We agreed members of the (Non-Proliferation Treaty) have right to peaceful nuclear energy," Larijani told reporters after meetings with Chinese Foreign Minister Li Zhaoxing and State Councilor Tang Jiaxuan.
In turn, Tang told Larijani that all "parties concerned should step up diplomatic efforts to create favorable conditions for the resumption of talks on the Iranian nuclear issue," China's official Xinhua News Agency said.
Iran is trying to prevent the U.S. and some European nations from bringing it before the U.N. Security Council, which can impose a range of sanctions or other measures over its alleged weapons program.
The United States and its European allies are encouraging China and other nations to vote to refer Iran's case to the Security Council when the International Atomic Energy Agency holds an emergency meeting on the issue on Feb. 2.
Russia, India and China are allies and trading partners of Iran who have been reluctant to see Tehran punished or ostracized through the Security Council. All three sit on the board of governors of the IAEA.
Even if the U.S. and its allies prevail in scheduling and winning a vote at the IAEA, it is not clear that the Security Council would then vote for severe penalties. The United States is not pushing for tough economic sanctions now but has not specified what action it wants instead.
China, as one of five, veto-wielding permanent members of the Council, could block any punitive action against Tehran.
Beijing opposes "arbitrary sanctions or threat of sanctions," Kong said. "It only complicates matters."
China's hesitation over the Security Council referral has prompted suggestions that Beijing wants to avoid angering Iran, a major oil source for its energy-hungry economy.
The West fears that Iran's uranium enrichment program is a precursor to making nuclear weapons, but Tehran says its intentions are peaceful and that it wants only civilian nuclear energy.
On Wednesday, Larijani met with Russian Security Council chief Igor Ivanov in Moscow.
He later told reporters that Tehran welcomes. But, he said, the proposal needs more work and threatened to renew full-scale uranium enrichment if his country is referred to the U.N. Security Council.
Some critics say that Tehran is using the proposal, under which Iranian uranium would be enriched in Russia and returned to Iran for use in the country's reactors, to stall for time as diplomatic pressure over its nuclear activities mounts.
In Washington, U.S. President George W. Bush said it was "important for us to exhaust all diplomacy" in dealing with Iran.
The Russian proposal offered the best chance for resolving the impasse, Bush told The Wall Street Journal, but if such efforts don't work, "clearly, there's a set of different options available through the Security Council, and now we're working with our friends to review those options."
Iran removed International Atomic Energy Agency seals from equipment Jan. 10, ending a 15-month moratorium, and announced it would restart research on nuclear fuel including what it described as small-scale enrichment.
The move led Germany, Britain and France to call for the Feb. 2 emergency board session.