Germany is hosting the latest effort to broker a truce to end five years of civil war in Syria. Increasing violence in Aleppo threatens to topple ceasefire efforts entirely.
Negotiations over Syrian peace talks began in Berlin on Wednesday, with government officials from Germany and France meeting with representatives from the Syrian opposition and the United Nations.
The talks seek to finalize a new truce agreement, initially brokered in Geneva this week, between regime troops and rebel forces.
But a surge of violence that erupted on April 22 and has claimed more than 270 lives in and around the divided city of Aleppo is threatening to undermine efforts to revive peace negotiations.
Russia, an ally of the Assad regime, maintains an end to the fighting in Aleppo is imminent, while US Secretary of State John Kerry warned Assad of "repercussions" if the ceasefire did not hold.
"If Assad does not adhere to [the new ceasefire], there will clearly be repercussions and one of them may be the total destruction of the ceasefire and they go back to war," said Kerry after a previous round of talks in Geneva on Tuesday.
Wednesday's meeting in Berlin will be hosted by German Foreign Minister Frank-Walter Steinmeier and attended by his French counterpart Jean-Marc Ayrault, UN Syria envoy Staffan de Mistura, and Syrian opposition leader Riad Hijab.
UN meeting later
France and Britain have called for an emergency meeting of the UN Security Council for later in the day on Wednesday as the situation in Aleppo continues to deteriorate.
France's UN ambassador Francois Delattre said on Tuesday that the situation in Aleppo was similar to that of Sarajevo during the Balkan conflict of the mid-1990s.
Fresh fighting in Aleppo on Tuesday included a rocket attack on a maternity hospital in which at least 19 people were killed.
"Aleppo is burning and it is crucial that we focus on this top priority issue," British UN Ambassador Matthew Rycroft said.
Syria will also be on the agenda of a meeting in the German city of Stuttgart between members of the US-led military coalition conducting airstrikes in Syria against the self-proclaimed "Islamic State" (IS). US Defense Secretary Ash Carter will host the meeting at a US military base.
mz/msh (Reuters, AFP, AP)