* Russia, China join rest of Security Council in vote
* U.N. chief says Syria must withdraw from urban areas
* Shelling hits districts of Homs city
* "Look, world, what they are doing," videomaker screams
By Louis Charbonneau and Oliver Holmes
UNITED NATIONS/BEIRUT, April 14 (Reuters) - Russia and China joined the rest of the U.N. Security Council on Saturday to authorise deployment of up to 30 unarmed observers to monitor Syria's fragile ceasefire as activists reported more deaths in the country and renewed shelling of Homs.
The resolution by the 15-nation Security Council is the first it has approved since the anti-government uprising in Syria began 13 months ago.
Moscow and Beijing twice vetoed council resolutions condemning Syrian President Bashar al-Assad's assault on protesters opposed to his rule that has killed thousands of civilians.
A spokesman for U.N.-Arab League mediator Kofi Annan had said on Friday that the first group of observers was on stand-by and ready to fly to Syria as soon as the council approved their deployment. Annan is planning for an observer force that will have up to 250 monitors.
U.N. Secretary-General Ban Ki-moon in a statement released after a meeting in Geneva said the Syrian government had the prime responsibility to stop the violence and withdraw its forces from urban areas in line with Annan's peace plan.
"The Secretary-General reiterated that it is the government of Syria which has the primary responsibility to stop the violence and withdraw its forces," the statement said.
Opposition activists said at least six people were killed in Syria on Saturday and also reported the first shelling, in the city of Homs, by forces loyal to Assad, since the U.N.-Arab League-brokered ceasefire took effect three days ago.
The Syrian Observatory for Human Rights said four people were killed during a funeral march in Aleppo, one by shelling in Homs and a sixth succumbed to wounds inflicted by torture in the central town of Rastan, straddling the Damascus-Aleppo road.
A video, shot in a destroyed part of what the cameraman says is the Homs neighbourhood of al-Qarabis, showed two tanks rushing through the streets to the sound of heavy gunfire and explosions.
"Look with your own eyes. Look, world. Watch what they are doing," the man making the video screams as a tank raises its turret.
The Syrian state news agency SANA said "armed terrorists" killed five people in ambushes around the country on Saturday, and kidnapped a parliamentary candidate from the north.
An army colonel also was kidnapped in the central city of Hama. "Colonel Mohammed Awad's car was intercepted by a terrorist group and he was kidnapped at gunpoint," SANA said.
The Syrian government repeatedly has denied access to journalists, making it impossible to verify the reports independently.
NO SIGN DIVISIONS OVERCOME
Despite Saturday's unanimous vote at the Security Council, there were no signs that the divisions that have prevented it from taking action on the crisis have been overcome.
Syria's close ally and arms supplier Moscow was satisfied with the final draft of the resolution, though Russian U.N. Ambassador Vitaly Churkin made clear that there were limits to the kind of U.N. action Moscow could support.
"Out of respect for the sovereignty of Syria we have cautioned against destructive attempts at external interference or imposing any kind of illusory fixes," he said.
Russia has accused the United States and Europe of tricking it into using a U.N. mandate to protect civilians in Libya to enable NATO engage in "regime change." Russia abstained from a March 2011 vote and allowed a council resolution authorizing "all necessary measures" to protect Libyan civilians to pass.
French Ambassador Gerard Araud added that the newfound unity on the council may not be permanent. "Our consensus is fragile," he said.
Before agreeing to support what was originally a U.S.-drafted text, Russia had demanded the U.S. and European delegations dilute it so that it would not "demand" that Syria comply with the resolution. The approved resolution uses softer language so that it "calls upon" Syria to implement it.
Churkin also demanded that the council urge the opposition as well as the Syrian government to change its behaviour.
The approved resolution has the council "condemning the widespread violations of human rights by the Syrian authorities, as well as any human rights abuses by armed groups, recalling that those responsible shall be held accountable."
It calls on "all parties, including the opposition, immediately to cease all armed violence in all its forms."
The text also includes a vague warning to Damascus, saying the council would "assess the implementation of this resolution and to consider further steps as appropriate."
Syrian Ambassador Bashar Ja'afari reiterated Damascus's commitment to Annan's six-point peace plan, which calls for an end to fighting, withdrawal of troops, dialogue between the government and opposition and a "political transition" for the country.
"The time for violence is gone," he said, though he accused the opposition of "50 violations" of the truce since Thursday.
Annan had asked the council to approve the deployment of an advance team of monitors as soon as possible.
Western council members welcomed the adoption of the resolution but had harsh words for Assad's government.
U.S. Ambassador Susan Rice condemned what she said was Damascus's "murderous rampage" over the last year, adding that the sporadic violence that has broken out since Thursday's ceasefire casts doubt on the government's commitment to peace.
Asked if the Syrian forces' shelling on Saturday of the battered city of Homs was a violation of the ceasefire, Rice said "absolutely."
VIOLENCE IN ALEPPO, HOMS
State news agency SANA and opposition groups traded blame on Saturday for gunfire in Syria's second city of Aleppo that activists said killed four and wounded three.
In a video, reportedly filmed in the Hay al-Etha neighbourhood, the sound of gunfire and an explosion can be heard as men holding the Syrian revolutionary flag and children scatter from what appears to be a demonstration.
SANA said: "Armed terrorist groups spread in Hay al-Etha, opened fire randomly and attacked public and private property."
In another video, dozens of people, some with medical masks wrapped around their faces, run amid the sound gunshots and two men drag an injured man along the street.
"We are in a state of war," the camera-bearer screams before running over to film a young man whose head is dripping with blood.
SANA said its own television building in the same neighbourhood was attacked by armed groups, but could not confirm casualties.
"Terrorist groups on Saturday opened fire randomly in al-Etha, attacked public and private properties and beleaguered the TV and Radio headquarters in the city," it said.
Hopes that the truce would put an end to the bullets that have frightened off peaceful protesters for months were quashed when forces loyal to Assad shot dead five protesters after Friday prayers, activists reported.
They said that security forces came out in strength in many cities to prevent protesters from mounting major rallies against Assad.
The United Nations estimates that Assad's forces have killed more than 9,000 people since the uprising began. Authorities blame the violence on foreign-backed militants who they say have killed more than 2,500 soldiers and police.