Russia says it will not attend a Western-backed international conference in Tunis about Syria's crisis.
Russia's Foreign Ministry said in a statement that the meeting supported only the Syrian opposition's cause, and that the interests of those who support the government in Damascus "will not be represented."
Chinese authorities refused to say whether they would attend the meeting of the so-called Friends of Syria group on February 24.
The group, which brings together several European and Arab countries, has been created in response to a joint veto by China and Russia of a United Nations Security Council resolution condemning the Syrian regime's bloody crackdown on antigovernment protests.
Meanwhile, Syrian activists say at least 17 people have been killed and scores wounded in the latest shelling by government forces targeting antiregime strongholds in the central city of Homs.
Activists say the regime has been bolstering its forces, including deploying tanks, outside Homs, in what activists fear could be a possible operation to storm the city.
Thousands of residents are reported to have fled the Baba Amr area of Homs to escape government forces.
Homs has been under siege for the past 18 days, and activists say hundreds of people have been killed by troops.
The reports cannot be independently confirmed, as the Syrian regime has barred foreign media from operating the country since the popular uprising against President Bashar al-Assad begun nearly a year ago.