The presidents of Russia and China on Monday called on Iran to fulfill the UN Security Council's resolutions over its disputed nuclear program.
Vladimir Putin and Hu Jintao also said in a joint statement that their countries - permanent, veto-wielding Security Council members - were ready to "search for a comprehensive, long-term and mutually acceptable solution to the Iranian nuclear problem."
"Russia and China are calling on Iran to take the necessary constructive steps to fulfill the UN Security Council resolutions and (International Atomic Energy Agency) board decisions and believe that Iran ... has the right to pursue peaceful use of nuclear energy while observing its obligations under the Nuclear Nonproliferation Treaty," the statement said.
They emphasized again that the increasingly tense dispute should be resolved "exclusively through peaceful means."
Russia and China joined other members of the Security Council on Saturday in voting to impose new sanctions on Iran. The sanctions included the banning of Iranian arms exports and the freezing of assets of 28 people and organizations involved in Iran's nuclear and missile programs.
Iran rejected the sanctions and later announced a partial suspension of cooperation with the International Atomic Energy Agency.
The visit by Hu to Moscow comes amid efforts by both countries to bolster what they say is a "strategic partnership" forged since the 1991 Soviet collapse. Before Hu's arrival, Russian and Chinese officials said that North Korea's nuclear efforts - as well as Iran's - would be on the agenda.
"Our relations are developing very actively, this concerns economic, political and international relations," Putin told Hu at the start of talks. "The level of cooperation is high in the sphere of military-technical cooperation and between our military institutions. I am sure that your visit will play a significant role in developing bilateral ties."
"Partnership and strategic cooperation between Russian and China have undergone 10 years of development. During this period, there have been uninterrupted successes," Hu said.
Like Russia, China has been reluctant to join the United States and other Western nations in an aggressive push for punitive sanctions against Iran, which says its nuclear programs are of a peaceful nature.
Washington and some of its allies fear the Iranian efforts are a cover for producing atomic weapons.
Earlier on Monday, the Russian state-run company building Iran's first atomic power plant said that Teheran had made its first payment toward the delayed construction of the Bushehr plant since a dispute over financing halted the project.
Moscow and Teheran have been at loggerheads over financing of the plant, and Russia earlier said that nuclear fuel would not be supplied this month, as had been planned. The delays prompted Russia to indefinitely postpone the reactor's launch, set for September.
Iran, meanwhile, angrily denied falling behind in payments and accused Russia of caving in to US pressure to take a tougher line on Tehran for defying international demands to halt parts of its nuclear program.
Russian officials denied media speculation that it was putting political pressure on Iran under cover of the financial dispute.
"The fact that our Iranian partners have overcome their difficulties is positive, however, it far from compensates for the requirements of the (project) that have arisen during the period of nonpayment," Atomstroiexport spokesman Sergei Novikov said in a statement.
The company also said the new payment was just half of the monthly amount needed for a normal construction schedule to be resumed.