By Nikolai Gorshkov BBC correspondent in Moscow

The leaders of Russia, China and four Central Asian states have adopted a charter for their regional security bloc, the Shanghai Co-operation Organisation (SCO), at a summit in St Petersburg.

The six leaders have also signed into being a joint agency to coordinate their efforts to combat terrorism and drug-trafficking in the region.

Russia and China are the driving force behind the bloc

The charter effectively transforms the hitherto loose grouping of Russia, China, Kazakhstan, Tajikistan, Uzbekistan and Kyrgyzstan into a fully-fledged international organisation with a permanent secretariat based in Beijing.

Its main aims are to fight terrorism, prevent conflicts and promote security in Central Asia.

The SCO was set up five years ago at the initiative of Russia and China, which were looking for ways to offset what they denounced as the US global domination.

But their project to build a regional counterbalance to America's might was put on a backburner after 11 September, when President Vladimir Putin gave a quick go-ahead for US military deployment in Central Asia and supported American action in Afghanistan.

Chinese concerns

Now the Russian leader is seeking to allay China's concerns about the increasingly warm ties between Moscow and the West.

In a political declaration signed at the summit, its members reiterate their support for a multilateral system of international security based on the principles of the United Nations and declare that their regional bloc is open to any country in the world.

There have been reports that India and Pakistan are also considering joining the SCO.

The organisation has urged the two to step back from the current confrontation over Kashmir and resume political dialogue.