The head of the UN ceasefire monitoring mission in Syria has given a bleak assessment of the task his team faces as UN chief Ban Ki-moon pledged to accelerate the deployment of additional observers.
Major-General Robert Mood has called on all sides to step up efforts to negotiate a peaceful solution to the conflict that has killed thousands of people since March 2011.
"The aspirations of the Syrian people for reduction in violence on a political track is something we share," he said, speaking to reporters in Damascus.
"That's our role, but we need all stakeholders inside [and] outside Syria to decide with the moral courage of people like Nelson Mandela, for example, to refrain from violence."
And he said: "No volume of observers can achieve a progressive drop and a permanent end to the violence if the commitment to give dialogue a chance is not genuine from all internal and external factors".
There are 257 monitors in Syria, but the mission is looking increasingly powerless to stop the violence.
Ban Ki-moon, the UN secretary-general, on Friday called again for all parties in the country to abide by a six-point peace plan proposed by UN-Arab League envoy Kofi Annan and said the UN was accelerating its deployment of its monitoring mission.
"We are almost reaching the authorised 300 monitors. It may be realised very soon. With this deployment of 300 monitors and some civilian staff, we hope that this will contribute to realising the complete cessation of violence by all sides. It is important so that inclusive political dialogue can start for political resolution of this issue," Ban said.
Protests in Aleppo
The comments came as Syrian forces reportedly fired tear gas and live ammunition to disperse protesters in the city of Aleppo on Friday, wounding several people.
In-depth coverage of escalating violence across Syria
Activist Mohammad Saeed said it was city's largest demonstration yet, with more than 10,000 people marching in the Salaheddine and al-Shaar districts and nearly as many more elsewhere in the city.
"The number of protesters is increasing every day," Saeed said.
Students uploaded a video purportedly showing them taking cover in a UN car while Syrian soldiers beat others nearby.
Thousands of people elsewhere in the country also staged anti-government rallies in solidarity with Aleppo, where a raid on dormitories at Aleppo University killed four students earlier this month and forced the temporary closure of the state-run school.
Friday is the main day of protests across Syria and this week's demonstrations were dedicated to "The Heroes of Aleppo University".
Meanwhile, activists said government troops shelled the central town of Rastan, which opposition fighters have controlled for months.
UN investigating Damascus bombings
Ban, who on Thursday said he believed last week's deadly bombings in Damascus were the work of al-Qaeda, said the UN was still investigating who was responsible for the attacks which killed at least 50 people and injured hundreds.
Al Jazeera's Hashem Ahelbarra reports how trade
with Turkey has been affected by the conflict in Syria
"Having seen the scale and sophistication of these terrorist attacks, one might think that this terrorist attack was done by a certain group with organization and clear intent," Ban said.
The blasts were the deadliest attacks in the Syrian capital since the uprising against President Bashar al-Assad began.
Ban said on Thursday that there had been two attacks against unarmed UN monitors trying to reduce the violence in the country.
"The deployment of monitors has some dampening effect, the number of violence has reduced but not enough, not all the violence have stopped," Ban said while addressing a youth group at UN headquarters in New York.
"We are trying out best efforts to protect the civilian population."
Ban said at least 10,000 people had been killed in the conflict.
Syria says that it is facing a "terrorist" conspiracy funded and directed from abroad. Earlier this month, Syrian officials sent the UN the names of 26 foreign nationals it said had been apprehended after coming to fight in the country.
It described 20 of those as members of al-Qaeda who had entered the country from Turkey.