"It all depends on the country. If it expresses the desire its application is considered. The SCO, like any serious international organization, does not invite or force anyone," Vorobyov, who is also the presidential special envoy to the SCO, told Vremya Novostei daily.
"The SCO is open for cooperation and has got new observer members," he added. Mongolia became a SCO observer last year, and India, Pakistan and Iran were granted observer status on Tuesday at the summit in the Kazakh capital, Astana.
The SCO comprises Russia, Kazakhstan, Uzbekistan, China, Tajikistan and Kyrgyzstan.
"This cooperation has no geographic limits. A country may be located anywhere but it should respect the SCO and be interested in cooperation," Vorobyov said.
The increase in the number of observers "will be useful for the SCO and the countries given this status, because regional security problems are closely connected with their interests," he said.
Vorobyov also said that a SCO-Afghanistan contact group would be set up soon.
"We should help Afghanistan fight against radicalism and promote economic development" to prevent drug trafficking from the country.
The SCO cannot admit new members as no relevant procedure has been worked out.
"However, the SCO Charter does not rule out the possibility," Vorobyov added.