Three years since the start of the uprising, nine million people have been displaced by fighting.
Arab League monitors in Syria have expressed concern about the worsening security situation in the country, as one observer reported seeing snipers in the city of Deraa.
The observer, in Syria as part of an Arab League mission to oversee the end of a bloody crackdown on protests, warned the government of President Bashar al-Assad of consequences if the snipers were not removed immediately.
“We saw snipers in the town, we saw them with our own eyes,” the observer told residents in a conversation filmed and posted online on Friday.
“We’re going to ask the government to remove them immediately. We’ll be in touch with the Arab League back in Cairo. If the snipers are not gone in 24 hours, then there will be other measures taken.”
The violence continued in Syria on Saturday, and activists said at least three people were killed as anti-government street protests continued.
A day earlier, security forces fired on protesters in Deraa, Hama and Idlib, despite the presence of nearly 100 Arab League observers deployed to ensure the government complies with the terms of the league’s plan to end the crackdown on dissent.
The orange-jacketed observers have been seen taking pictures of the destruction, visiting families of victims of the crackdown and taking notes.
“Since yesterday we’re getting more statements from observers very, very critical of the situation there,” said Al Jazeera’s Hashem Ahelbarra, speaking from Antakya, Turkey.
“This is going to force the international community to take drastic action,” he said, adding that the UN security council could take part in that action.
Up to 100,000 people were reported to have protested on Friday in the Damascus suburb of Douma, where the observers were within “hearing distance” from where troops opened fire on demonstrators.
In addition to tear gas, the UK-based Syrian Observatory of Human Rights said security forces used nail bombs against protesters.
Amid the violence, two leading Syrian opposition parties signed a draft agreement to unite against Assad, and set up a “parliamentary system for a democratic, pluralistic civil state and guarantees the exchange of power through elections”.
The leading opposition group in exile, the Syrian National Council (SNC), signed the deal on Saturday with the National Co-ordination Committee (NCC), a group whose majority is inside Syria and which had disagreed with the SNC’s earlier calls for foreign intervention.
Ashraf al-Moqdad, an activist with the Damascus Declaration, speaks about the draft agreement
Under their new pact, the two sides “reject any military intervention that harms the sovereignty or stability of the country, without considering Arab intervention to be foreign”.
But Ashraf al-Moqdad, an activist with another Syrian opposition group, the Damascus Declaration, told Al Jazeera that the deal will be ineffective.
“The first thing the regime aims or fights for is to stop all international interference… This is not what the Syrian people have called for,” he said.
“We know what we need to do: We need to go to the international community; we need to go to the Security Council, and that’s when real things will happen and the murders, the crimes against humanity will stop. Nothing else will stop it.”
The deal also outlines a one-year transitional period, which could be renewed once if necessary. The agreement is to be presented to other opposition groups at a conference next month.
Without international intervention beyond the Arab League, Moqdad said that the deal will be unproductive.
“The Arab League is impotent, it has no teeth, it can’t force nothing,” he told Al Jazeera.
The Arab League observers began their mission on Tuesday in Homs, the city which has seen the brunt of the violence.
Since then, they have spread out in small groups across Syrian provinces, including the restive Idlib province in the north, Hama in the centre, and the southern province of Deraa, where the uprising began.
But activists say attacks on protesters have continued despite the presence of monitors.
The Local Co-ordination Committees, an activist network, said at least 130 people, including six children, have been killed since the observers began their one-month mission.
Al Jazeera’s Dorsa Jabbari, reporting from Beirut in neighbouring Lebanon, said on Friday that protesters were eager to show the observers the situation on the ground and have their stories heard, but some residents were more hesitant to speak.
“[The observers] are being followed by Syrian forces as part of the agreement, so they are responsible for their safety,” she said. “So some residents don’t feel they have the freedom to speak in front of Syrian authorities in front of the observers.”