"The memorandums, which are a process ahead of the countries' entry, lay a legal foundation for the organization to steadily expand its membership in the future," he said.

The SCO is a six-member intergovernmental organization founded in Shanghai on June 15, 2001.

Grouping China, Kazakhstan, Kyrgyzstan, Russia, Tajikistan and Uzbekistan, the SCO covers a total area of over 30 million square kilometers and accounts for a quarter of the world's population.

Taking security and economy as its two wheels, the group agreed last year to kick off procedures for including India and Pakistan as members.

"By admitting India and Pakistan into the bloc, the SCO is facing up to a security threat in the broader Eurasian region," said Ye Hailin, researcher on South Asian issues at the CASS. "The group will be combating security threats like terrorism in a broader regional space."

Also at Friday's summit, the leaders voiced shared support for China on the South China Sea issue, saying that disputes should be peacefully resolved through negotiations involving those directly involved and opposing internationalization and intervention from external forces.

Xinhua contributed to this story.

Contact the writers at anbaijie@chinadaily.com.cn