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.
Some 9.5 million people have been forced to flee their homes.
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”.
Mr Brahimi’s discussions with the two sides on Saturday lasted a matter of minutes
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.
Mr Brahimi said the government’s stance “raises the suspicion of the opposition that the government doesn’t want to discuss [a transitional government] at all.”
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, focusing instead on the need to fight what it calls “terrorists”.
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.
He said no date had been set for a third round of talks.
The agreement to allow aid into Homs was a rare success from the talks
So far, the only agreement in the latest negotiations was to allow civilians to leave the besieged city of Homs and aid to enter.
Otherwise the talks, which started six days ago, have failed to narrow the gap between the government of President Bashar al-Assad and the opposition.
Correspondents say at least 5,000 people are believed to have died since the first round of the Geneva talks began on 22 January.
US President Barack Obama said he was considering ways of putting more pressure on President Assad, though he did not expect any resolution in the short term.
Speaking in California, where he was meeting Jordan’s King Abdullah, he said: “There will be some intermediate steps that we can take applying more pressure to the Assad regime and we are going to be continuing to work with all the parties concerned to try to move forward on a diplomatic solution.”
Mr Obama did not disclose what steps he has under consideration.
Earlier, UN humanitarian chief Valerie Amos urged the UN Security Council to act immediately to ensure more humanitarian access in Syria.
The Security Council has been deadlocked over aid deliveries in Syria, where millions have been forced to flee their homes.