Leaders of 12 former republics of the Soviet Union have not agreed on a way forward for the loose confederation, known as the CIS, at a meeting held in the ancient city of Kazan. The meeting revealed rifts following recent political shifts in several of the member countries.
The central Russian city of Kazan in the mostly-Muslim Russian republic of Tatarstan is holding a gala celebration marking the 1000th anniversary of its founding.
Many visitors have arrived to take part in the festivities, which included a gala concert.
Also attending are the 12 leaders of the former Soviet republics that are part of what is called the Commonwealth of Independent States, or CIS.
The CIS, which was formed as the Soviet Union collapsed in 1991, has long served as a means to discuss economic and political issues of the now-independent countries that were once ruled with an iron hand from Moscow.
Some of those states now seem reluctant to foster such close ties with Moscow.
Ukraine, Georgia, Kyrgyzstan and the small southern republic of Moldova have all elected more pro-reform governments in recent years, and some say they may soon set up their own regional organization to reflect the new reality.
Even Russian President Vladimir Putin seemed to acknowledge what this means for the CIS. In a final statement at the end of the summit, he said "the question of modernizing the CIS will be deep and very difficult."
The leaders did sign agreements concerning the fight against terrorism and how to deal with illegal immigration.
But the emerging differences within the bloc are increasingly clear, according to Andrei Kortunov of the New Eurasian Foundation in Moscow.
"Indeed, there are a number of countries that tend to be more liberal, more democratic and more reform-minded than others," he noted. "The danger is, you have this split, and the split might have very serious geopolitical and geoeconomic consequences."
Last week, Russia's foreign minister said Moscow may change its long-standing policy of providing gas and oil at lower prices to other CIS states, seen as a kind of warning to Ukraine, Georgia and Moldova.
Mr. Kortunov says, if this happens, it is likely to be implemented gradually, and would reflect new international terms of trade.