The UN Security Council has scheduled a vote on a draft resolution on Saturday to send up to 300 unarmed military observers to Syria, despite US and European concerns that the government has yet to fully implement a ceasefire.
The 15-nation council held three hours of closed-door discussions late on Friday to iron out differences between separate draft resolutions submitted by the US and Russia.
The drafts called for an "immediate end to all violence and human rights violations, securing humanitarian access and facilitating a Syrian-led political transition leading to a democratic, plural political system".
Envoys reached a preliminary agreement on a draft resolution on the Syrian conflict, a crisis that has left the council divided since it erupted 13 months ago.
But there was a possibility the deal could fall through since council members must seek final approval from their capitals overnight.
"It's possible not everybody will have instructions at that point [11am]," Susan Rice, the US ambassador to the UN and president of the Security Council this month, said.
"It's possible there will not be an agreed text at that point, we'll see, and we'll regroup accordingly."
Britain, France and Russia would also like a deal.
"I hope there's going to be a unanimous vote tomorrow," Vitaly Churkin, the Russian ambassador, said.
"The Syrian government and the opposition must know that the Security Council will be authorising the full-fledged mandate so we hope it's going to send a strong and good political signal."
The diplomatic developments came as activists said government troops fired tear gas and bullets on thousands of protesters who spilled out of mosques after noon prayers on Friday.
State media reported that bombs and shootings killed 17 soldiers.
Under the proposed Security Council resolution, the full mission would have an initial three-month mandate to monitor the cessation of hostilities which started on April 12.
Activists say more than 130 people have been killed since the ceasefire started, however, and UN chief Ban Ki-moon pointedly told the council this week that President Bashar al-Assad had not kept a commitment to withdraw troops and heavy weapons from population centres.
European nations had wanted the threat of sanctions to be included in the resolution if Assad did not keep the commitments. But the final draft text talks only of backing the resolution with "further steps as appropriate".
It calls for Ban to report back to the council on Syria's compliance within 15 days.
There are eight monitors already in Syria from Morocco, Brazil, Belgium, Switzerland and Norway after the council authorised an advance team of up to 30 on Saturday.
A new resolution is needed for a further "initial deployment" of up to 300 as recommended by Ban.
'Violations of human rights'
Some council members have expressed reluctance to give swift approval for an expanded observer mission because of concern about the failure of the Syrian government to halt the violence, return troops to barracks and withdraw heavy weapons.
The US and European countries have insisted that Syria must accept the use of UN planes and helicopters by the UN mission, which will be called UNSMIS.
The Russian draft resolution did not mention air assets and was less critical of Syria's government than the European text.
The compromise draft urges Syria to reach an agreement with the UN on "appropriate air transportation assets" and condemns the government for "widespread violations of human rights".
Syria has dismissed any need for UN aircraft.
Ban has said helicopters and other military hardware would be needed by the monitors.
Annan's peace plan calls for an end to fighting by government security forces and rebels, withdrawal of heavy weapons from towns, the return of the army to barracks, humanitarian access and dialogue between the government and opposition aimed at a "political transition".
Opposition activists reported that at least 11 civilians were killed in government shelling and other attacks on Friday, the main day of the week for protests calling for the overthrow of Assad.
Protests were reported in Damascus and its suburbs, as well as in the northern city of Aleppo, the central regions of Hama and Homs, in eastern towns near the border with Iraq and in the southern province of Deraa.
Al Jazeera has obtained satellite images of the city of Homs, showing destruction and military presence
Demonstrators poured out of mosques onto the streets, calling for Assad's downfall and chanting in support of the country's rebel forces, activists said.
"Security is extremely tight in Damascus," Maath al-Shami, an activist, said, adding that despite the heavy presence of plainclothes security agents, there were protests in the capital's neighbourhoods of al-Qaboun, al-Midan, Barzeh and al-Mazzeh.
He said troops fired in the air to disperse the protesters. Activists also said troops fired bullets and tear gas at protesters in Aleppo as well as the central city of Hama.
In the rebel-held al-Khaldiyeh neighbourhood of Homs, a mortar round was striking every five minutes, according to the UK-based opposition group, Syrian Observatory for Human Rights (SOHR).
An amateur video posted online by activists showed thick black smoke billowing as shells apparently fell in a residential area.
Explosions and gunfire
The SOHR said eight civilians were killed in Homs on Friday, including a family of three whose home was struck by a shell. It reported three more civilians were killed by army fire in other parts of Syria.
Citing its network of sources on the ground, the SOHR said explosions and gunfire rang out in the town of Qusair, near the border with Lebanon.
Activists said the government was sending reinforcements to the town.
Meanwhile, Syria's state-run news agency SANA said a large roadside bomb went off in the southern village of Sahm al-Golan, near the Israeli-occupied Golan Heights, killing 10 soldiers.
A separate explosion, also in southern Syria, killed five soldiers, the agency said, adding that two more soldiers were killed in separate shooting attacks.