The UN-backed peace plan for Syria is on "track", the office of international mediator Kofi Annan has said, as activists reported renewed violence in the country.
Ahmad Fawzi, Annan's spokesperson, said on Friday negotiations were being "conducted under the radar" involving the Syrian government and its opposition to cease all hostilities.
But Fawzi said there were continuing violations of truce conditions such as heavy weapons in populated areas, despite "small signs of compliance".
"The Annan plan is on track… And a crisis that has been going on for more than a year is not going to be resolved in a day or a week,” Fawzi told a UN briefing in Geneva.
His comments came as the Local Co-ordination Committees, an opposition activist network, reported the deaths of 33 people in renewed violence across the country. Massive anti-government protests were also reported.
In the central city of Hama, government forces used gunfire to disperse protesters in two districts of the city and in another town of the same province, activists reported.
Abu Omar, a local activist, said troops also fired on demonstrators outside the main mosque in the Damascus neighbourhood of Jubar.
Similar incidents were reported in other neighbourhoods of the capital and surrounding towns as well as in Hasakeh, in the northeast of the country.
Opposition activists had called for nationwide protests under the slogan "Our commitment [to the revolution] is our salvation".
Anti-regime demonstrations have been staged after prayers each Friday since the revolt against President Bashar al-Assad's rule broke out in March 2011.
Expanding observer mission
The London-based Syrian Observatory for Human Rights said protests were also taking place on Friday in northern Aleppo province, in the eastern province of Deir Ezzor and in the northwestern province of Idlib.
Amateur video posted on YouTube by activists showed demonstrators in Irbin, a town in Damascus province, carrying a banner that read: "Dear [UN] observers, thank you for your visit and goodbye."
UN truce observers have been touring restive parts of the country where the UN estimates 9,000 people have been killed since the uprising began more than a year ago.
The head of the observer mission, Norwegian Major General Robert Mood, told reporters on Thursday in Syria that there was still "a good chance and an opportunity" to break the cycle of violence.
Fawzi said Mood's team would have "around 50" observers on the ground by the end of Friday, and that the United Nations had obtained commitments from different nations for 150 of the 300 observers that the UN Security Council authorised.
"It's not an advance team any longer," Fawzi said. "The numbers are growing every day."
He also said Mood's truce observers are not being targeted, despite suicide blasts occurring near a hotel where some of them were staying.
But Fawzi acknowledged that "there are days when things are progressing in a satisfactory manner, and there are days where we feel that it's a rough ride".
He said that even on days when there is progress "we are horrified by the extent of violence we see on the ground".
'No other option'
Al Jazeera’s Rula Amin, reporting from Beirut in neighbouring Lebanon, said: "[Fawzi] made it very clear that there is no other option, and they're going to work on this option no matter its chances of success."
"It seems that the UN is trying to find a way around every obstacle. They're trying to make it work,” she said.
In-depth coverage of escalating violence across Syria
"They feel that the presence of the observers on the ground did make a difference - that it did reduce the level of violence."
On Thursday, the Obama administration offered a bleaker view that it may be time for the world to acknowledge the cease-fire was not holding in Syria, and other approach might be needed.
The White House press secretary, Jay Carney, told reporters that "if the regime's intransigence continues, the international community is going to have to admit defeat".
US officials say the plan is failing mainly because of Syrian government violations.
But both Assad's government and the Syrian opposition are blaming each other for flouting the cease-fire.
Annan, the joint UN-Arab League envoy, is scheduled to brief the UN Security Council on Tuesday by videoconference from Geneva with the latest assessment on implementation of his six-point peace plan.
The plan aims at ending the violence, bringing in relief, releasing detainees and forging a political process to address grievances in Syria.