International envoy Kofi Annan has urged the UN Security Council to send a message to the Syrian government and
the opposition that there will be "consequences" if they don't comply with demands for an immediate cease-fire.
"We had not been successful so far in ending the violence - this is still a fact today," said Annan during a press briefing on Wednesday.
"If we reunite, if the council speaks with one voice, that one voice will be much more powerful."
Russia and China, key allies of Syrian President Bashar al-Assad and veto-wielding council members, have blocked repeated attempts by the United States and its European allies to even threaten "consequences" - a diplomatic code word for sanctions.
However, Bashar Ja'afari, the Syrian ambassador to the UN said any party calling for sanctions is " not genuinely supportive of the mission of Mr. Kofi Annan".
A UN diplomat, speaking on condition of anonymity because Annan's videoconference briefing from Geneva was at a closed session, said that the council should insist on implementation of its resolutions including Annan's six-point peace plan.
That plan calls for an immediate cease-fire and withdrawal of heavy weapons from populated areas by the Syrian government to be followed by an opposition cessation of hostilities.
Al Jazeera's Scott Heidler, reporting from the UN in New York, said there is also talk of a "bottom up" approach.
"That is, work on the grassroots level politically to set up some kind of infrastructure, so that when peace talks do eventually come into play, they have that infrastructure there so they can start negotiating," said Heidler.
The UN sent a 300-strong unarmed observer mission for 90 days to oversee the cessation of violence and monitor implementation of the Annan plan.
It was forced to withdraw from key conflict areas because of the escalating fighting and the council must decide what to do about extending its mandate which expires on July 20.
The Russian plan
Meanwhile, Syria's opposition failed on Wednesday to persuade Russiato drop ally Assad and warned that this will only prolong the violence.
Russia put forth its own draft resolution on Tuesday, asking that the existing mandate for the observer mission be extended with few changes, while another draft resolution - this one by the P3 (the US, UK and France) - is also expected to be delivered to the UN by tomorrow.
Our correspondent said the P3 plan will likely have more "teeth" - probably in the form of sanctions.
In-depth coverage of escalating violence across Syria
"They are saying that yes, we need to have this observer mission in Syria to see if the six points of Kofi Annan's plan are being adhered to, but there needs to be a stick along with that, there has to be teeth to this resolution, probably along the lines of sanctions," said Heidler.
But as fresh clashes across the country challenged Assad's beleaguered regime, Russia refused to shift its stand on the conflict, the Syrian National Council (SNC) said after talks in Moscow with Foreign Minister Sergei Lavrov.
Abdel Basset Sieda, head of the exiled SNC, reacted angrily to the failure.
"We reject the Russian policy - however it is presented - as this policy of supporting the regime is allowing the violence to continue," he told reporters after the talks.
"The Syrian people continue to suffer because of the position of Russia at the UN Security Council where Russia has used its veto" to block two resolutions against Assad's regime, he said.
"As a result, the killings and shootings continue and the Syrian regime is using these weapons that Russia gave to Syria against its own people."