The CSTO, a post-Soviet regional security bloc comprising Armenia, Belarus, Kazakhstan, Kyrgyzstan, Russia, Uzbekistan and Tajikistan, has already agreed to create a joint rapid-reaction force, but Russia is preparing a new, larger-scale project.
"The work is being conducted in all areas, and a number of documents have been adopted," the Kommersant newspaper quoted an unidentified source in the Foreign Ministry as saying.
"It will be a purely military structure, built to ensure security in Central Asia in case of an act of aggression," the source said.
Russia already has joint military contingents with Belarus and Armenia in the CSTO framework.
The new force will comprise large military units from five countries - Kazakhstan, Kyrgyzstan, Russia, Uzbekistan and Tajikistan.
"It will include armored and artillery units, and a naval flotilla in the Caspian Sea," CSTO press secretary Vitaly Strugovets said earlier.
The creation of a powerful military contingent in Central Asia reflects Moscow's drive to make the CSTO a pro-Russian military bloc, rivaling NATO forces in Europe.
Russia's security strategy until 2020, recently approved by President Dmitry Medvedev, envisions the CSTO as "a key mechanism to counter regional military challenges and threats."
CSTO leaders are scheduled to gather for a summit in Moscow on June 14 to sign an agreement on the creation of a joint rapid-reaction force as an interim step toward the creation of a larger military grouping.
The rapid-reaction force will include an airborne division and an air assault brigade from Russia, and an air assault brigade from Kazakhstan. The remaining members will contribute a battalion-size force each, although Uzbekistan would "delegate" its detachments to take part in operations on an ad hoc basis.