The United Nations should keep threatening Syrian authorities with sanctions to "breathe life" into a faltering plan to end the worsening 16-month conflict, Syria's main opposition umbrella group said on Tuesday before a planned U.N. Security Council vote on the issue.
The Syrian National Council said it has been meeting in New York with ambassadors from countries on the U.N. Security Council to press for stronger action from the 15-member body to enforce international envoy Kofi Annan's six-point peace plan for Syria.
"The absence of enforcing mechanisms and the lack of any stipulation of consequences for the regime's non-compliance has hereto rendered the Annan plan ... ineffective and has led to a loss of trust in its viability by the Syrians," Bassma Kodmani, head of the Syrian group's foreign relations, told a news conference.
The Security Council is scheduled to vote on Wednesday on a Western-backed resolution that threatens President Bashar al-Assad's government with sanctions if it does not stop using heavy weapons in towns and cities.
Russia has already declared it will block the move.
The Security Council has until Friday to decide the fate of the U.N. observer mission in Syria.
The resolution, proposed by Britain, the United States, France and Germany, would extend that U.N. mission for 45 days and place Mr. Annan's peace plan under Chapter 7 of the U.N. Charter.
Chapter 7 allows the 15-member Security Council to authorize actions ranging from diplomatic and economic sanctions to military intervention, but U.S. officials have said they are talking about sanctions on Syria, not military intervention.
Mr. Kodmani described a resolution under Chapter 7 "as a very last chance for breathing life into the (Annan) plan."
Russia and China have already vetoed U.N. Security Council resolutions designed to pressure Mr. Assad to halt the violence.
"The message of another veto on a resolution at the U.N. Security Council will send the wrong message both to the regime and the Syrian people," Mr. Kodmani said. "It is a message of a blank check to continue the violence, to continue crushing the population and to continue the massacres."
Russia, an ally of Syria, has also put forward a resolution to extend the U.N. mission for 90 days, but it does not contain a threat of sanctions. It was not clear when or if Russia plans to put its draft resolution to a vote.
"The credibility of the U.N. is at stake," said a senior European official, who did not want to be identified.
"It has happened already when we look at the public opinion in the Arab world, they are doubting the effectiveness of the joint special envoy, they are doubting the effectiveness of the Security Council," he said.
"It's very difficult to explain to the average Syrian who has had his home destroyed, loses his father and mother ... why the international community has yet to really act," said Syrian opposition official Khalid Saleh.
If the U.N. mission in Syria is renewed, Secretary-General Ban Ki-moon has recommended shifting the emphasis of its work from military observers to civilian staff focusing on a political solution and issues that include human rights.
The U.N. observers suspended most of their monitoring on June 16 because of the spiral of violence that has brought Syria to the brink of civil war.
"This is absolutely the last chance for the Security Council to act responsibly and to give it some teeth through Chapter 7 and if they fail to do so we are seeking other options," said Syrian opposition official Najib Ghadbian, without elaborating.
Mr. Assad's forces have killed more than 15,000 people in increasingly brutal efforts to suppress an anti-government revolt that began in March last year, according to Western sources. Mr. Assad's government has asserted that rebels have killed several thousand members of its security forces.