BEIJING: China on Wednesday called on Syria to heed a plan aimed at bringing peace to the conflict-ridden country, saying it was "deeply concerned" by the situation.

"China calls on the Syrian government to respond to the six-point proposal," foreign ministry spokesman Liu Weimin said, referring to the plan put forward by U.N.-Arab League envoy Kofi Annan.

"Violence and conflict in Syria still persists... China is deeply concerned about this," Liu told a regular news briefing.

China backed the plan after Annan met with top Chinese leaders in Beijing last month.

Annan's plan had called for the withdrawal of Syrian troops from populated centers on Tuesday, and then a complete cessation of combat in the following 48 hours.

That 48-hour period is to end at 6:00 am Damascus time (0300 GMT) on Thursday.

But Syrian President Bashar Assad failed to observe the Tuesday deadline to withdraw government forces from urban areas.

Liu said the political settlement of the issue had reached a "critical stage" and opposition parties as well should cease fighting.

Syria showed no let up in assaults on protest hubs Wednesday.

But Annan, who is visiting Iran, said there was still a chance to salvage a peace plan for a complete halt to hostilities within 24 hours.