China said Wednesday it supported a political transition in Syria and was not attached to President Bashar al-Assad as it defended its record during a visit by US Secretary of State Hillary Clinton.

Clinton, meeting in Beijing with the country's top leadership, reiterated she was "disappointed" by the vetoes of China and Russia of UN resolutions that would have threatened action against Assad to end the spiraling bloodshed.

But Chinese officials continued to warn against an "outside formula" to end the armed conflict.

Chinese Foreign Minister Yang Jiechi called for all sides to end fighting, telling a joint news conference with Clinton: "Let me emphasise that China is not partial to any individual or any party."

Yang called on all nations to exert "a positive influence" to persuade the sides in Syria "to adopt a realistic, calm and constructive attitude so that there can be an early beginning of political dialogue and transition".

But he warned against the use of outside force to end the conflict that activists say has killed more than 26,000 people -- a sensitive notion for one-party China.

"I think history will judge that China's position on the Syrian question is promotion of the appropriate handling and resolution of the Syrian issue," he said.

Foreign ministry spokesman Hong Lei, speaking after Yang's remarks, reiterated that China is opposed to intervention in Syria.

"We believe that the imposition of an outside formula on Syria is counter-productive," he said at a regular press briefing in Beijing.

"We oppose any acts of armed intervention in Syria and we also oppose outside sanctions against Syria since they will only escalate tensions."

The spokesman also said that the future of Syria should be "decided by its own people" and that the "sovereignty, political integrity and independence of Syria should be respected".

"We hope that all parties in Syria will stop the violence and end the killing of innocent civilians and serve to end the bloodshed," Hong Lei added.

China has repeatedly called for political dialogue and efforts by the United Nations to resolve the crisis in Syria.

Beijing has also joined Russia to repeatedly use their vetoes to scuttle UN Security Council resolutions aimed at tackling the deadly conflict, putting them at odds with fellow permanent members like the US.

Clinton urged further action on Syria, saying: "The longer the conflict goes on, the greater the risk that it spills over borders and destabilises neighbouring countries.

"The best course of action remains to unite the Security Council behind real consequences if President Assad continues to brutalise his own people and threaten the security of the region."

While China has regularly voiced its opposition to using outside intervention, Russia is the primary supporter of Assad and has come under US criticism for supplying arms as he puts down the biggest threat to his family's four-decade grip on power.

Clinton is expected to meet this weekend with Russian Foreign Minister Sergei Lavrov during an Asia-Pacific summit in Vladivostok.