A senior Chinese envoy called for all sides in Syria to stop the violence and for elections to go ahead peacefully after Damascus talks with President Bashar al-Assad on Saturday, state media said.
The meeting came after a day of violence in which a human rights watchdog said at least 30 people were killed as protests spread to several well-to-do neighbourhoods of the capital for the first time and security forces unleashed their heaviest pounding yet of the flashpoint central city of Homs.
Activists called for a "day of disobedience" in Damascus on Sunday to galvanise support for the protest movement.
"The position of China is to call on the government, the opposition and the rebels to halt acts of violence immediately," Vice Foreign Minister Zhai Jun said after his talks with Assad.
Zhai, whose government has twice joined Moscow in blocking UN Security Council condemnation of the Damascus regime's deadly crackdown on an 11-month uprising, said it was vital that "calm be restored as quickly as possibly as that serves the interests of the Syrian people," state television reported.
"We hope that the referendum on a new constitution as well as the forthcoming parliamentary elections pass off calmly," he said.
On Thursday, Syrian opposition groups rejected a newly drafted constitution that could end nearly five decades of single-party rule, and urged voters to boycott a February 26 referendum on the charter.
One of them, the National Coordination Committee for Democratic Change, told AFP "it is impossible for us to take part in this referendum before a stop to the violence and killings" which rights groups say has killed more than 6,000 people since March last year.
Zhai's meeting with Assad followed talks with his counterpart, Faisal Meqdad, late on Friday after which he said the international community must respect Syria's sovereignty.
"We exchanged views on ways to strengthen our cooperation in the face of this difficult period in Syria," Zhai said.
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"The sovereignty, unity, independence and territorial integrity of Syria must be respected by all sides and by the international community," the official Syrian Arab News Agency quoted him as saying.
"China hopes that national dialogue and reforms will move forward in Syria," he added.
On Thursday, before heading to Damascus, Zhai said Beijing opposed armed intervention and forced "regime change" in Syria.
China and Russia have faced a barrage of criticism for blocking action by the UN Security Council, including from Arab nations with which Beijing normally has good ties.
"We urge the Syrian government and all of its political parties to immediately and fully end all acts of violence and quickly restore stability and normal social order," said Zhai.
"China condemns all acts of violence against innocent civilians" and "does not approve of armed intervention or forcing so-called 'regime change,'" he was quoted as saying by the official Xinhua news agency.
The Syrian Observatory for Human Rights said four people, two of them teenagers, were killed when security forces opened fire on Friday's "unprecedented" demonstrations in Damascus.
"It's the first time that the protests have spread to well-to-do neighbourhoods," said Moaz Shami of the Local Coordination Committees, which organise demonstrations on the ground, adding that a total of 49 were counted in the capital on Friday.
In a message to Damascus residents on their "Syrian Revolution 2011" Facebook page, activists said: "The blood of the martyrs exhorts you to disobedience."
In Homs, rockets crashed into strongholds of resistance at the rate of four a minute on Friday, according to one activist, who warned that the city -- Syria's third largest -- faces a humanitarian crisis.
Thirteen of the dead were in the Homs district of Baba Amr.
"It's the most violent in 14 days. It's unbelievable -- extreme violence the like of which we have never seen before," said Hadi Abdullah of the General Commission of the Syrian Revolution.