Monitors say at least 45 more people have been killed on Tuesday during pro-government bombardment of the rebel-held eastern Ghouta area near the Syrian capital, Damascus.
The UK-based Syrian Observatory for Human Rights estimates at least 190 people have been killed and 850 injured since the renewed bombardment began on Sunday.
The war monitor says this is the heaviest one-day death toll in the area in three years.
More than 100 people were killed in air raids, rocket strikes and shelling, according to the UK-based Syrian Observatory for Human Rights.
The Observatory says the intesnsified bombing is in preparation for a pro-government ground offensive against the enclave and that a rebel group there had foiled an attempt by Syria's army to advance on al-Marj overnight.
The Union of Medical Care and Relief Organisations, a coalition of international agencies that funds hospitals in Syria, says bombs have hit five hospitals in eastern Ghouta on Monday.
Has the Syrian government said anything?
Not yet. Neither the Syrian military nor Russia has commented on the renewed bombardment in eastern Ghouta.
However, they have regularly said they do not target civilians.
What has the international community said?
The UN has called for an immediate ceasefire in the area. The organisation says the situation is "spiralling out of control" after an "extreme escalation in hostilities".
In Geneva, the UN children's fund issued a blank "statement" to express its outrage at the casualties among Syrian children, saying it had run out of words.
What is the context?
The violence in eastern Ghouta is part of a wider escalation in warfare on several fronts in Syria in recent months as President Bashar al-Assad pushes to end the seven-year rebellion against him.
Assad's most powerful ally Russia has been following a diplomatic track at the same time as the upturn in fighting. This has resulted in the establishment of several "de-escalation zones".
Eastern Ghouta is in one of the areas where violence is meant to be contained but the agreement does not include a former al-Qaeda affiliate which has a small presence there.
Other insurgent groups in eastern Ghouta, including Islamist factions, say the Syrian government and Russia are using the jihadist presence as a pretext to continue their bombardment.