Geneva: The UN special envoy for Syria has warned that if troubled peace talks in Switzerland failed, then "all hope would be lost".
"A failure is always possible, particularly after five years of horrible war," Staffan de Mistura said on Tuesday on Swiss television channel Radio Television Suisse.
"But if there is a failure this time, after two previous meetings in Geneva on Syria, then all hope will be lost," de Mistura said.
De Mistura is trying to coax representatives of the government of President Bashar al-Assad and the opposition umbrella into indirect peace talks.
The negotiations have, however, after several days, failed to move beyond the preliminary stage, with chief government negotiator Bashar al-Jaafari on yesterday saying the opposition was "not serious".
The main opposition umbrella group on Tuesday cancelled a planned meeting with de Mistura, angry at what it called "unprecedented" Russian air strikes in support of regime forces near Aleppo.