In their joint declaration concluding the first day of the Chinese leader's three-day visit to Moscow, Vladimir Putin and Hu Jintao said Iran had the right to peaceful nuclear energy if it observed the Nuclear Non-Proliferation Treaty (NPT).
"Russia and China believe that Iran's nuclear problem must be resolved purely through peaceful means and negotiations," said the joint declaration.
Iran resumed nuclear research last January, saying it needs energy. The move caused international concerns that Tehran could be working on a secret weapons program.
Russia and China, which belong to the six international negotiators on Iran, urged the Islamic Republic to implement resolutions of the UN Security Council and the IAEA Board of Governors.
The 15-nation UN Security Council voted Saturday to toughen sanctions against Iran over its failure to meet the requirements set in December's resolution and give up nuclear research.
The resolution also proposed restarting negotiations from scratch, and promised aid in civilian nuclear energy development and direct investment in key sectors of the economy in return for Iran's consent to abandon uranium enrichment.
Iran responded to the new sanctions by saying it would reduce cooperation with IAEA inspectors until its nuclear file is returned to the agency from the UN Security Council. President Mahmoud Ahmadinejad said Sunday the resolution would not stop his country's nuclear program "for a second."
Russia, which is building a $1-billion nuclear power plant in southern Iran, has been following a softer stance on Iran and opposed any tighter sanctions against the country.
The Russian and Chinese leaders also reaffirmed their commitment to bringing about a solution to North Korea's nuclear problem.
"Russia and China reiterate their positions in favor of the Korean Peninsula's non-nuclear status, which is of vital importance to peace and security in the Asia Pacific Region," the declaration said.
Russia and China are two of six negotiators on North Korea, which also include South and North Korea, Japan, and the United States.
The talks, held since 2003, made a breakthrough in February when the North agreed to shut down its nuclear reactor and the U.S. said it would unfreeze North Korean accounts in a Chinese bank in return. But negotiations stalled March 19-22 over delays with the transfer of money from the accounts.
The Russian and Chinese leaders also raised the question of weapons deployment in space and called for negotiations on an international agreement to prevent such programs.
Putin and Hu said "a special committee to discuss a relevant draft agreement should be re-established at a conference on disarmament in Geneva."
At their meeting in Moscow, Putin and Hu also agreed to maintain intensive cooperation in other international affairs, including within the Shanghai Cooperation Organization (SCO), the Russian leader said.
"We are positive that our joint efforts will help enhance the security of Russia and China, and will promote stability in Central Asia, in the Asia-Pacific Region and in the world as a whole," Putin said after Hu announced last week the SCO was preparing for further expansion.
Apart from Russia and China, the organization presently includes Kyrgyzstan, Kazakhstan, Tajikistan and Uzbekistan. India, Iran, Mongolia, Pakistan and Afghanistan have observer status.
The primary ambition of the SCO is to ensure regional security by combating drug trafficking, illegal arms trade, and trans-border crime. It also works to boost economic cooperation in the region and to create favorable conditions for trade and investment. Promotion of closer cultural and humanitarian ties is another important area of the alliance's activity.