"The SCO Charter allows new admissions, but the organization has yet to work out criteria and algorithm of such procedure," Alexander Losyukov was quoted by the Itar-Tass news agency as saying.

At the same time, he stressed that this does not mean the SCO will turn into a "closed club." According to Losyukov, there is "the readiness to expand mutually advantageous cooperation with the observe states in various areas."

"We are working on a mechanism for SCO dialogue cooperation with all interested countries and multilateral structures," he added.

"The SCO is committed to an open and equal dialogue, the development of partnership with other associations and countries. The range of issues for possible cooperation is quite broad: security, various economic projects, and humanitarian cooperation," he said.

Founded in Shanghai in 2001, the SCO was aimed at enhancing security, trade, cultural, military and justice cooperation among member countries. It groups Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, China and Russia. Mongolia, Pakistan, India and Iran are observer countries at SCO meetings.