President Vladimir Putin on Friday won the support of Iran and China at a regional summit on Russia's initiative for Syria to hand over its chemical weapons, which he said had proved the "serious intentions" of the Damascus regime.

Putin attended the summit of the Shanghai Cooperation Organisation (SCO), a regional security group sometimes seen as an eastern counterweight to NATO, in Kyrgyzstan a day after President Bashar al-Assad said he supported the Russian plan.

The leaders of the SCO, whose members include Russia, China and several Central Asian states, said in a communique that they supported the initiative and opposed any actions that could lead to a "further militarisation" of the situation in Syria.

Chinese President Xi Jinping, speaking at the summit in Bishkek, said his country welcomed Russia's plan and attached a lot of importance to the development of the situation in Syria.

"We support the Russian initiative to hand over Syrian chemical weapons under international control," Xi said.

Newly-elected Iranian President Hassan Rowhani, whose country has observer status at the SCO, said Tehran also fully backed the Russian initiative.

"We believe that the situation in Syria should be decided politically and without foreign military intervention. All influential and interested sides should lead a constructive dialogue in that direction," he added.

He recalled that Iran suffered horrendous casualties when Iraqi dictator Saddam Hussein used chemical weapons in the Iran-Iraq war in the 1980s.

"Iran, as the worst victim of the use of chemical weapons, favours their destruction across the world. The possibility that armed extremist groups could obtain chemical weapons is the biggest threat to the region," Rowhani said.

Iran and Russia have in recent years emerged as the last major allies of the Assad regime. China has throughout the conflict backed Russia's position but been far more circumspect in its public comments.

Putin said that the global community should welcome Syria's decision to join a ban on chemical weapons, saying it showed the "serious intentions" of Damascus.

"I believe we should welcome such a decision of the Syrian leadership. I would like to express hope that it will be a very serious step on the path to solving the Syrian crisis," Putin told the security summit.

"This confirms the serious intentions of our partners to go along this path," he said, referring to the regime of President Bashar al-Assad, whom the Kremlin has backed throughout the two-and-a-half-year conflict.

Speaking at the plenary session of the SCO summit, Putin reiterated his firm resistance to the use of force against Syria.

"Recent diplomatic efforts have allowed to reduce an immediate threat of a military operation," Putin said.

Russia has proposed that Damascus give up its chemical weapons in a bid to avoid threatened military strikes by the US.

Assad said he would join the ban on chemical weapons but insisted that Washington renounce the "politics of threats" if it wanted the plan to work.

On Friday, the top Russian and US diplomats were meeting for a second day of key talks to hammer out a plan to secure Syria's chemical weapons.