Syrian forces loyal to President Bashar al-Assad fought rebels near the border with Turkey on Friday, threatening a ceasefire brokered by United Nations peace envoy Kofi Annan.
Opposition activists called for mass demonstrations after Friday prayers to test how Assad's forces will tolerate a return to peaceful protest, as international pressure mounted for Damascus to fully comply with its commitments to Annan, by withdrawing troops and heavy weapons.
The U.N. Security Council was working on a resolution authorising the despatch of an advance party of U.N. observers to monitor the truce.
The British-based Syrian Observatory for Human Rights, citing activists' reports, said fighting broke out in the northwestern province of Idlib, close to the border with Turkey, after troops went to clear rebels out of the area.
Some of the gunmen pulled out when the shooting started, Observatory director Rami Abdulrahman said. There were no immediate reports of casualties and the fighting appeared to have stopped.
Syria's grassroots Local Coordination Committees, however, said there had been heavy gunfire in the village of Kherbet Joz, close to the Turkish frontier. Dozens of tanks were deployed on the edge of the village, it said.
Abdulrahman said the ceasefire which came into effect at dawn on Thursday appeared to be holding in the rest of the country, but there was still no sign of any army withdrawal.
He said at least four people were shot dead in Syria on Thursday. Three were killed by snipers in the city of Homs, the centre of opposition to Assad, and one man was shot dead at a checkpoint in the central province of Hama.
The Observatory also reported several demonstrations on Thursday night in the eastern city of Deir al Zor and the northern commercial hub of Aleppo. It said they were dispersed by security forces who fired into the air.
The United Nations says Assad's forces have killed 9,000 people since an uprising against him erupted 13 months ago. Authorities blame the violence on foreign-backed militants who they said have killed more than 2,500 police and soldiers.
World leaders welcomed the halt in fighting which had threatened to spill over into neighbouring countries and U.N. Secretary General Ban Ki-moon said the situation looked calmer.
The world is watching, however, with sceptical eyes since many promises previously made by the government of Syria have not been kept, he told a news conference in Geneva.
Annan wants up to 250 unarmed U.N. observers in Syria.
Ambassador Vitaly Churkin of Russia, which has supported the Syrian government in what it says is a battle against foreign-funded armed gangs, said the 15-member Security Council could adopt a resolution authorising the deployment on Friday.
The full-fledged mission will take some time to deploy ... If we are able to put 20 or 30 monitors (there) early next week, very good, Churkin said. If we are able to put more in the next few days that's even better.
A draft resolution by the United States included a vague threat of future action against Damascus, saying the council expresses its determination, in the event that the Syrian government does not implement its commitments, to consider further measures as appropriate.
PROTEST BY PERMIT
Along with the withdrawal of forces from population centres, U.N.-Arab League envoy Kofi Annan's six-point plan calls for talks with the opposition aimed at a political transition, the release of political prisoners, access for humanitarian aid and journalists, and for the authorities to respect freedom of association and the right to demonstrate peacefully.
Burhan Ghalioun, head of the opposition Syrian National Council (SNC), said he did not trust the authorities to allow the renewal of protests after Friday prayers, a feature of the uprising that has been subdued by violence in recent months.
The authorities, he said, had their hand on the trigger.
While we call on the Syrian people to protest strongly... we ask them to be cautious because the regime will not respect the ceasefire and will shoot, he told Reuters.
The Syrian Interior Ministry said only pre-authorised demonstrations would be permitted by police, a caveat which the opposition said did not bode well.
This is ridiculous, said an activist called Musab from Hama city, a focus of opposition activity and government bombardment along with Homs and Idlib. They will not give you permission and you will be taken to jail if you ask for it.
The SNC's spokesman said Assad could simply not afford to stop shooting, since that would allow a new wave of mass protests against his family's four decades of absolute power.
As soon as there is a real ceasefire, people will come out to the streets, demonstrating and demanding his removal, his stepping down. So I think the regime has to retaliate by opening fire again, spokesman Bassam Imadi told Reuters in Istanbul. But lets hope for the better.
Ban said there had been a surge in Syrian refugees fleeing to Turkey and Lebanon this week and an estimated 1 million people inside Syria now needed humanitarian assistance.
This ceasefire process is very fragile - it may be broken any time if, and when, there is another gunshot, Ban said. This is a very worrisome.
(Editing by Douglas Hamilton and Giles Elgood)