Iranian president Hassan Rouhani says he believes there is little hope of success for the Syrian peace talks.
Mr Rouhani’s remarks come as an international conference to try to resolve Syria’s civil war gets under way in the Swiss resort of Montreux.
Later this week in Geneva, Syria’s warring sides will sit down for their first face-to-face meeting since the conflict erupted in 2011.
Mr Rouhani said hopes are slim because some of the countries attending the talks “are behind instability” in Syria.
He spoke following a diplomatic snub to Iran after the UN withdrew its invitation to Tehran to attend the talks.
Iran has been Syrian president Bashar Assad’s main regional ally and a staunch supporter of his government.