US Secretary of State Hillary Clinton called Friday on all parties with influence in Syria to make a "concerted push" together to halt the conflict.
Clinton said there had been no "great breakthrough" during talks in Dublin on Thursday with her Russian counterpart Sergei Lavrov and the UN peace envoy Lakhdar Brahimi, but said there would be further meetings between officials.
"No one should have any illusions about how hard this remains," Clinton said during a visit to Northern Ireland.
"But all of us with any influence on the process, with any influence on the regime or the opposition, needs to be engaged with Brahimi for a concerted, sincere push to see what is possible in the face of the advancing developments on the ground."
Recent developments in Syria were "increasingly dangerous, not only to Syrians but to their neighbours," she added.
Clinton said she and the Russians would be sending officials for talks with Brahimi in the next few days to "talk about how we can operationalise the path foward."
She stressed again though that Syrian President Bashar al-Assad had to step aside, and could not play any part in a transition process.
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Brahimi said after Thursday's talks that he, Clinton and Lavrov all agreed the situation was "very, very, very bad" in Syria but "no sensational decisions" were reached.
"Both Minister Lavrov and I committed to support a renewed push by Brahimi and his team to work with all stake-holders in Syria to begin a political transition based on the outline we agreed to in Geneva," Clinton said.
"It was an important meeting but just the beginning."
Clinton is to travel to Marrakesh next week for a meeting of the Friends of the Syrian People, at which the United States may decide to recognise the new Syrian National Coalition as the sole representative of the Syrian people.
The Geneva accord, concluded by Brahimi's predecessor Kofi Annan, was signed onto by Moscow in June. But the Russians then balked at the idea of including punitive UN action if Syria refused to implement the deal.
Clinton stressed that the Geneva deal set out "clear steps toward a transition" and highlighted it was "not a one-sided dialogue."
"The United States stands with the Syrian people in insisting that any transition process result in a unified, democratic Syria."
UN chief Ban Ki-moon said Friday the use of chemical weapons by Syrian President Bashar al-Assad to combat the revolt would be an "outrageous crime".