The Syrian opposition's new leader said on Sunday that President Bashar al-Assad's regime was on its "last legs," even as Russia warned it would block any move at the UN to use force against its ally.
Western governments launched a push for tough new sanctions against Damascus amid an outcry over a series of massacres blamed by UN observers on pro-regime forces as troops killed at least 83 civilians on Saturday, a human rights watchdog said.
"We are entering a sensitive phase. The regime is on its last legs," Kurdish activist Abdel Basset Sayda told AFP shortly after he was named as the new leader of the opposition Syrian National Council.
"The multiplying massacres and shellings show that it is struggling," he added in allusion to a spate of mass killings of civilians, the most recent of which saw 20 people, most of them women and children, killed in the bombardment of a residential area of the southern city of Daraa on Saturday.
Sayda was elected as the SNC's new leader at a conference in Istanbul, replacing the opposition's first leader, Paris-based academic Burhan Ghalioun, who stepped down last month in the face of mounting splits that were undermining the group's credibility.
Activists accused Ghalioun of ignoring the Local Coordination Committees, which spearhead anti-government protests on the ground in Syria, and of giving the Muslim Brotherhood too big a role.
Sayda, who has lived in exile in Sweden for two decades, is seen as a consensus candidate capable of reconciling the rival factions within the SNC and of broadening its appeal among Syria's myriad of ethnic and confessional groups.
The 55-year-old does not belong to any political party and, although his name is not familiar to many Syrians, SNC officials say he is a "conciliatory" figure, "honest" and "independent".
The opposition grouping has been criticised for not representing the full diversity of Arabs, Kurds, Sunni Muslims, Alawites, Christians, Druze and other ethnic and religious groups in Syria.
Asked about his ambitions as SNC leader, Sayda said the opposition bloc "would focus its efforts on the international community to take a decisive move against the regime."
"We want to strengthen links with activists on the ground and the (rebel) Free Syrian Army, who we will support with all our means", he said.
"The Annan plan still exists but it has not been implemented," he added, in reference to a peace blueprint thrashed out by UN-Arab League envoy Kofi Annan that was supposed to begin with a ceasefire from April 12 but which has been violated daily.
"We will work for this plan to be included under Chapter VII of the UN Charter, to force the regime to implement it and to leave all options open," he said.
Chapter VII allows for sanctions and, in extreme cases, military action. But Russia and China, infuriated by the NATO campaign in Libya last year, have vowed to oppose any military intervention.
Russia will "not sanction the use of force at the United Nations Security Council," Foreign Minister Sergei Lavrov said on Saturday.
He said Moscow would be "glad" to support Assad's departure but only if Syrians themselves agreed on it.
Lavrov renewed Russian calls for an international conference on the more than 15-month-old conflict, with Syria's main regional ally Iran to be given a place at the table despite US opposition.
"We want this event to be effective," he told reporters.
"To say that Iran doesn't have a place because it is already to blame for everything and it's part of the problem and not part of the solution, this is thoughtless to say the least from the point of view of serious diplomacy."
Russia has said a conference on Syria is needed to overcome differences over how Annan's peace plan should be implemented.
Lavrov said Security Council permanent members Britain, China, France, Russia and the United States should take part alongside Syria's neighbours, Iran and the European Union and the Arab League.
Moscow wants to hold the forum "as soon as possible", Lavrov added.
His comments drew strong criticism from the SNC, which accused him of trying to "cover up the obvious and serious responsibility" of the Damascus government of "questioning the agenda of the Syrian opposition and the SNC in particular."
It said Moscow's policy poses "a major threat to the historic friendship between the Syrian and Russian peoples and to future relations between Russia and Syria's new democracy."
"We call upon the government of Russia to commit to the principles of international law to protect civilians," it added.
More than 13,500 people have been killed since the uprising against Assad's regime erupted in March last year, according to the Britain-based Syrian Observatory for Human Rights.