UPDATE 2-Annan to brief deadlocked UN council on Syria
* Syria says responded positively to Annan proposals
* U.N. Council resolution talks hinge on Annan briefing
* No signs of UN deadlock over Syria being broken (Adds diplomats, details, background)
UNITED NATIONS, March 14 (Reuters) - The U.N.-Arab League envoy on the Syrian crisis, Kofi Annan, will brief the U.N. Security Council on Friday about his peace mission, which diplomats say could breathe new life into stalled talks on a resolution aimed at ending the escalating violence.
Council diplomats say Annan's assessment of the crisis will be crucial to a bid by the United States and its European allies to pass a resolution that would also ensure humanitarian aid workers have access to besieged towns across the country. Russia and China have twice vetoed resolutions condemning Syria.
Talks between the five permanent Security Council members and Morocco on a draft resolution have stalled, but are expected to pick up again after Annan's briefing, diplomats said.
However, they say it remains unclear if Moscow will accept a resolution on Syria, where protests against President Bashar al-Assad began a year ago.
Russian Foreign Minister Sergei Lavrov told the Security Council during a special debate this week on the Arab Spring uprisings that Moscow would like the 15-nation body to reach consensus on a Syria resolution.
Russia, he said, could accept a resolution in line with its March 10 agreement with the Arab League, which urged an end to the violence, impartial monitoring, no outside interference, humanitarian access for all Syrians and support for Annan's push for talks between the government and the opposition.
A senior Western diplomat, speaking on condition of anonymity, said all those points were already covered in the U.S.-drafted resolution the five permanent members and Morocco have been discussing.
The main sticking points, he said, were Russia's insistence that the government and opposition stop fighting simultaneously and Moscow's push to assign equal blame to both sides. The United States, Gulf Arabs and Europeans say Assad's much-stronger and better-armed forces must stop fighting first.
"We are not going to accept a resolution that creates an equivalence between the regime and opposition," the diplomat said.
A less contentious, but still difficult issue is how to refer in the resolution to an Arab League plan that urges Assad to step aside, envoys said. Russia opposes clear endorsement of the plan, though Western diplomats said they could probably find an acceptable compromise Moscow and China could live with.
However, council envoys say there are no signs that permanent council members are close to breaking their deadlock. Negotiations on the resolution will likely remain on hold until after Annan's briefing on Friday, diplomats said.
Syria said on Wednesday it responded positively to proposals by Annan for ending the escalating violence that has killed thousands of civilians. Annan's spokesman had said questions remained over Syria's response.
The United Nations estimates Syrian security forces have killed well over 7,500 people. Syria said in December that "terrorists" had killed more than 2,000 soldiers and police.
Annan, a former United Nations secretary-general, will brief the U.N. Security Council via video conference. He met Assad in Damascus over the weekend and outlined proposals including a halt to fighting, humanitarian access and starting a political dialogue with the Syrian opposition.
U.N. Secretary-General Ban Ki-moon appealed to Assad on Monday to act within the next few days on peace proposals.
Russia, supported by China, has vigorously opposed action against Damascus by the 15-nation U.N. Security Council for more than six months.
The two veto powers have vowed to prevent Washington, Paris and London from pursuing Libya-style regime change in Syria, a strong ally of Moscow and home to the Russian navy's only warm-water port outside the former Soviet Union. (Editing by Vicki Allen and David Brunnstrom)