United Nations (U.N.) Special Envoy for Syria Staffan de Mistura attends a meeting on Syria with representatives of the five permanent members of the Security Council (P5) at the United Nations European headquarters in Geneva, Switzerland, January 13, 2016. REUTERS/Denis Balibouse

GENEVA (Reuters) - The United Nations Special Envoy for Syria said on Wednesday that peace talks might not start as planned in Geneva on Jan. 25th but that major powers must maintain diplomatic pressure on the warring sides to come to the table.

Staffan de Mistura, in an interview on CNN from the Swiss resort of Davos, said he would know on Sunday whether the negotiations could start the next day, but added that they had to be “serious talks about peace” linked to “concrete demonstrations” such as ceasefires and aid convoys.

“I believe we can start talks, perhaps not on the 25th (of January), but we need to maintain the pressure and the momentum,” he said. He said he believed Russia, Syria’s ally which has been bombing rebel positions for months, had a strong interest in not being embroiled for too long in the conflict.

Despite their rift, Iran and Saudi Arabia “probably realize that the time has come to try to find a political solution (on Syria) which will be a compromise”, de Mistura said.