The Syrian opposition's High Negotiations Committee has backed efforts towards planned peace talks in Kazakhstan between the Syrian government and rebel groups.
The committee said on Saturday that it viewed the meeting as a preliminary step for resuming the next round of political negotiations in Geneva.
A nationwide ceasefire began in Syria on December 30 to pave the way for new peace talks, which Russia hopes to convene in the Kazakh capital Astana later this month with Turkish and Iranian support.
Turkey and Russia have decided to invite the United States to Syria peace talks due to be held this month in the Kazakh capital Astana, Turkey's foreign minister said on Saturday.
Mevlut Cavusoglu reiterated that Turkey remained opposed to the inclusion of the People's Protection Units (YPG), the Syrian Kurdish armed group, in the peace talks.
Syria has been ravaged by violence since widespread protests in March 2011 calling for President Bashar al-Assad's ouster.
Death and displacement
More than 310,000 people have been killed and over half the population has been forced to flee.
Diplomatic efforts to end the conflict have thus far failed, but Moscow and Ankara are hoping that the peace talks in Astana later this month will lead to a political solution.
After a two-day meeting in Riyadh, the High Negotiations Committee leading opposition body said it would extend its support to an anti-government military delegation attending those negotiations.
"Concerning the forthcoming meeting in Astana, the (High Negotiations) Committee stresses its support to the military delegation... and expresses hope that the meeting would reinforce the truce," the HNC stated.
It said the meeting in Astana "paves the way for political talks" in Geneva in early February, hosted by the United Nations.
The Washington Post reported late Friday that Russia had invited US President-elect Donald Trump's incoming administration to the meeting, by passing President Barack Obama's team.
The Astana talks are scheduled to begin just three days after Trump is inaugurated.
Outbreaks of violence
The ceasefire deal appeared increasingly strained on Saturday, with outbreaks of violence in northwest Syria and near the capital.
Fresh raids on Saturday in the town of Maarat Masrin in the northwest province of Idlib killed eight people, most of them civilians, the Observatory stated.
A day earlier, three civiliansincluding a childwere killed in strikes on the nearby town of Orum al-Joz, Abdel Rahman stated.
Idlib province is controlled by a rebel alliance led by Jabhat Fateh al-Sham (JFS), which changed its name from al-Nusra Front after breaking ties with al-Qaeda last year.
Like ISIL, JFS is excluded from the truce deal.
New clashes also broke out Saturday in Wadi Baradathe main source of water for Damascus.
Water supplies from the area to around 5.5 million people in the capital and its outskirts have been cut since December 22 because of fighting.
Rebels and government troops had reached a local agreement Friday so that water access could be restored, but the Observatory reported a resumption of violence Saturday.
"Regime forces and (Lebanese movement) Hezbollah violated the agreement" by battering a town in Wadi Barada with rocket fire, Abdel Rahman told AFP.
"They took advantage of the halt in military activities there to advance and flex their muscles," he stated.
Aljazeera