The head of the Syrian opposition's negotiating team said he was not optimistic about upcoming peace talks, casting further doubt on whether the group will attend meetings planned for Friday in Geneva.
Assad al-Zoubi was quoted by Arabic news channel Al-Hadath saying recent diplomatic moves "did not give cause for optimism over the negotiations".
He added that the United Nations special envoy for Syria, Staffan de Mistura, "cannot impose conditions" on the opposition team.
The High Negotiations Council (HNC) was due to meet in Riyadh later on Tuesday to decide whether to attend the Geneva session.
It has already said the opposition will stay away unless the Syrian government and its Russian allies halt air strikes and lift sieges on towns.
De Mistura has said the Geneva meeting will aim to kick off six months of talks, first seeking a ceasefire, later working towards a political settlement to a war that has killed more than 250,000 people and forced than 10 million to flee.