Russian President Vladimir Putin has hosted a summit of former Soviet republics and called for unity among them.

Putin presided over an informal summit of the Commonwealth of Independent States in St. Petersburg on Tuesday. Russia is expected to chair the group next year.

He told the other leaders that it is not by chance that they had gone through history as a unified state.

He also said he sees the main task of the Russian presidency as strengthening the close ties and friendship between the peoples of the CIS countries.

One of the participants was Armenian Prime Minister Nikol Pashinyan.

He is believed to have been frustrated with Russia since ethnic Armenian forces were forced to surrender in the disputed region of Nagorno-Karabakh following a military offensive by Azerbaijan in September.

Pashinyan apparently believes that Moscow failed to fulfill its role as Armenia's ally.

He skipped a summit of a Russia-led military alliance of former Soviet states in late November, and is seen as seeking closer ties with the West.

Putin is believed to be trying to keep a grip on Armenia and other nations that Russia considers as its sphere of influence.