China on Thursday confirmed that presidents of all the Shanghai Cooperation Organization (SCO) member states will attend the organization's summit slated for June 15 in Shanghai.

Presidents of Mongolia, Pakistan and Iran, three SCO observers, will also attend the summit, Chinese Foreign Ministry spokesman Liu Jianchao told a news briefing.

On the sidelines of the summit, Chinese President Hu Jintao will hold bilateral meetings with presidents of the SCO members and observers, including Iran's President Mahmud Ahmadinejad, Liu said.

The spokesman said China had discussed Iran's nuclear issue with the country in the past and will continue to do so in the future to improve mutual understanding.

"China will continue to make positive efforts to help peacefully solve the Iran nuclear issue through negotiations," Liusaid when asked whether the nuclear issue will be raised at the meeting between Hu and Ahmadinejad.

India, another SCO observer, will send its Minister of Petroleum and Natural Gas Murli Deora to the summit, Liu said.

Liu also confirmed that Afghan President Hamid Karzai, Executive Secretary Vladimir Rushailo of the Commonwealth of Independent States and Deputy Secretary-General Wilfrido. V. Villacorta of the Association of Southeast Asian Nations will attend the summit as guests.