The UN mediator Lakhdar Brahimi has apologised to the Syrian people after peace talks in Geneva ended without making progress.
He had held final discussions with both sides in Geneva in a last-ditch bid to break the stalemate between the Syrian government and opposition.
He said the main sticking point was the government, which refused again to talk about a transitional governing body.
The conflict in Syria has claimed more than 100,000 lives since March 2011.
The discussions on Saturday morning lasted just 27 minutes, after which Mr Brahimi emerged looking tired to address reporters, the BBC’s Imogen Foulkes reports from Geneva.
Mr Brahimi apologised to the Syrian people, admitting that the talks “had not come out with very much”.
Although the two sides had agreed on an agenda for the next round, Mr Brahimi said the government had rejected his suggestion to begin a third round by spending a day focusing on combating violence and terrorism, and a second day discussing a transitional government.
The opposition has long insisted on a transitional government that does not include President Bashar al-Assad or any of his loyalists.
The government has always rejected this and said there is no question of Mr Assad leaving power.
Mr Brahimi said both sides needed “to go back to their base” for consultations and to think about whether they wanted the process to continue or not.