DAMASCUS: China and Russia said Wednesday they were “decisively against” intervention or regime change in Syria as Arab and Western calls mounted for tougher international action in the 15-month conflict.

As rebel fighters stepped up their attacks in and around Damascus, Russian Foreign Minister Sergei Lavrov warned that regime change in Syria would lead the Middle East to “catastrophe”.

US Secretary of State Hillary Clinton, who has voiced mounting frustration with the Chinese and Russian position, was to discuss the situation with allies in Istanbul later on Wednesday, a Turkish diplomatic source said.

In a joint statement issued after two days of talks between Russian President Vladimir Putin and Chinese leaders, Beijing and Moscow said they strongly opposed intervention and regime change in Syria.

“Russia and China are decisively against attempts to regulate the Syrian crisis with outside military intervention, as well as imposing... a policy of regime change,” the statement said.

Speaking in the Chinese capital, the Russian foreign minister urged the international community to resist calls from the exiled opposition to help oust President Bashar al-Assad's regime.

“(Opposition groups) outside Syria appeal to the world community more and more to bomb the Assad regime, to change this regime,” Lavrov told reporters in the Chinese capital.

“This is very risky, I would even say it is a way that will bring the region to catastrophe.” Lavrov hit out at the rebel Free Syrian Army's announcement on Friday that it was no longer bound by a six-point peace plan brokered by UN-Arab League envoy Kofi Annan and endorsed by the UN Security Council in a resolution backed by both Beijing and Moscow.

Lavrov said it was important for all states that have sway over Syria's opposition groups to convince them to stop escalating the situation, adding that Beijing and Moscow would continue in lockstep over Syria, opposing foreign intervention and forced regime change.

The two nations have vetoed two Security Council resolutions criticising Assad's regime, but they voted in support of Annan's blueprint to end the conflict, in which more than 13,500 people have died since March last year, according to the Syrian Observatory for Human Rights.

The plan was supposed to begin with a ceasefire from April 12 but as violence has raged on daily despite the deployment of nearly 300 UN observers, doubts have emerged about its effectiveness.