Central and South Asian leaders sat down Wednesday for security talks with their Russian and Chinese counterparts at the annual summit of the Shanghai Cooperation Organization in Kazakhstan.

The leaders were expected to discuss expanding the core six-member group for the first time since it was founded 10 years ago. India, Pakistan and Iran all are seeking full membership in the group, which in the past has sought to limit U.S. influence in Central Asia.

Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan already are full members of the group. Mongolia is not seeking to change its observer status.

In private talks ahead of the meeting Tuesday, Chinese President Hu Jintao urged Iranian Prime Minister Mahmoud Ahmadinejad to quickly resume talks with leading world powers about his country's nuclear program. He said Iranian steps to establish trust and promote dialogue would be in the interest not only of Iran but of the Middle East as a whole.

Mr. Ahmadinejad replied that Iran is willing to return to talks with the five permanent members of the United Nations Security Council plus Germany. But last week he rejected a report by the United Nations nuclear agency, saying it would have no bearing on Iran continuing its nuclear activities.