Air strikes by the Syrian government on a rebel-held enclave have continued despite a ceasefire resolution passed by the UN Security Council on Saturday.
Hundreds of people have died in a week of bombardment of the Eastern Ghouta enclave near the capital, Damascus.
The latest attacks include a ground offensive that began hours after the UN urged a 30-day truce "without delay".
On Sunday, France and Germany called on Russia to put pressure on the Syrian government to honour the ceasefire.
Speaking to Russian President Vladimir Putin in a joint telephone conversation, German Chancellor Angela Merkel and French President Emmanuel Macron have asked for help with implementing the UN resolution.
The UN resolution was agreed to allow for aid deliveries and medical evacuations, but operations against the biggest jihadist rebel groups are not covered by the truce.
The region is the last major rebel-held area near the capital Damascus.