France and Iran have voiced concern over escalating violence in Syria, echoing warnings from the United States and Russia as fighting near the city of Aleppo puts more pressure on a fragile truce agreement.
The already widely violated "cessation of hostilities" agreement brokered by Russia and the United States has been strained to breaking point by an upsurge in fighting between Syrian government forces and rebels near Aleppo.
The escalation underlines the already bleak outlook for peace talks set to reconvene this week in Geneva.
The United Nations says the talks will resume on Wednesday, and the government delegation has said it is ready to join the talks from Friday.
With President Bashar al-Assad buoyed by Russian and Iranian military support, the Damascus government is due to hold parliamentary elections on Wednesday, a vote seen by Mr Assad's opponents as illegitimate and provocative.
Iran said an increase in ceasefire violations could harm the political process a day after Russia said it had asked the United States to stop a mobilisation of militants near Aleppo, Syria's biggest city until the conflict erupted in 2011.
Iranian Deputy Foreign Minister Hossein Amir-Abdollahian, speaking after a meeting with UN Special Envoy Staffan de Mistura in Tehran on Tuesday, blamed the "increasing activities of armed groups" for the violations.
France, which backs the opposition, also expressed concern, but blamed the other side.
"It warns that the impact of the regime and its allies' offensives around Aleppo and Eastern Ghouta are a threat to the cessation of hostilities," government spokesman Romain Nadal said.
The Eastern Ghouta is an opposition-held area near Damascus.
Syria's civil war has killed more than 250,000 people, created the world's worst refugee crisis, allowed for the rise of Islamic State and drawn in regional and international powers.
The intervention of Russia swung the war in Mr Assad's favour.