Russian news agencies are quoting President Vladimir Putin's representative to the Shanghai Cooperation Organization (SCO) as saying Iran, which has observer status in the organization, can only become a full member when United Nations sanctions against the Islamic republic are lifted.
Kirill Barsky reportedly said the Shanghai group's rules prohibit a country from joining if the UN has imposed sanctions.
Iran is currently under four rounds of UN Security Council sanctions over Tehran's nuclear program.
Iranian President Mahmud Ahmadinejad traveled to Beijing to attend the June 6 Shanghai group summit.
Iran has been seeking membership of the Shanghai group for several years, as have Mongolia, Pakistan, and India.
The Shanghai group, which focuses on regional security and cooperation issues, includes China, Russia, Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan.
Based on reporting by ITAR-TASS and Interfax