Russia offered the UN Security Council a new, stronger draft resolution on the violence in Syria, lifting Western hopes of UN action after the killing of 27 Syrian soldiers by deserters raised the spectre of a slide into civil war.

Western envoys said the Russian text was too weak, but they were willing to negotiate over it, offering the council a chance to overcome its deadlock and issue its first resolution on Syria's nine-month-old crackdown on protesters.

An activist group said Syrian army deserters killed 27 soldiers on Thursday in and near the southern city of Deraa, in some of the deadliest attacks on forces loyal to President Bashar al-Assad since the uprising against his rule began.

The Syrian Observatory for Human Rights said 12 soldiers were killed in Deraa, where protests against Assad first erupted in March, and 15 at a checkpoint east of the city.

The high casualties among security forces suggested coordinated strikes by army rebels who have escalated attacks, raising fears that Syria might be slipping towards civil war.

The United Nations says 5,000 civilians have been killed in Assad's crackdown on protests inspired by uprisings elsewhere in the Arab world. Assad has denied any orders were issued to kill demonstrators and says gunmen have killed 1,100 of his forces.

It is the most serious challenge to the 11-year rule of Assad, 46, whose family is from the minority Alawite sect that has held power in majority Sunni Muslim Syria for four decades.

Western diplomats believe a firm Security Council resolution backed by Russia, Syria's longstanding ally, could make a real difference to the crisis.

In October, Russia and China vetoed a West European draft resolution that threatened sanctions. Russia has circulated its own draft twice, but Western nations said it made an unacceptable attempt to assign blame equally to government and opposition.

The draft circulated unexpectedly by Russia on Thursday expands and toughens Moscow's previous text, adding a new reference to 'disproportionate use of force by Syrian authorities'.

The draft, obtained by Reuters, also 'urges the Syrian government to put an end to suppression of those exercising their rights to freedom of expression, peaceful assembly and association'.

Russia's UN Ambassador Vitaly Churkin told reporters it 'considerably strengthens all aspects of the previous text' and that 'clearly the Syrian authorities are singled out in a number of instances'.

He said Russia did not believe both sides in Syria were equally responsible for violence, but acknowledged it called on all parties to halt violence and contained no threat of sanctions, which he said Moscow continued to oppose.

Western officials welcomed the Russian move, but French Ambassador Gerard Araud said it needed 'a lot of amendments'.

In Washington, U.S. Secretary of State Hillary Clinton said she could not support some parts of the draft, but 'hopefully we can work with the Russians, who for the first time at least are recognising that this is a matter that needs to go to the Security Council'.

In London, British Foreign Office Minister Alistair Burt said Russia might hold the key to tightening sanctions on Syria, but Britain would also look at ways of imposing new sanctions on Damascus through the European Union.

'We will continue to look for new ways in energy, in transport, as well as financial restrictions, to put pressure on the Syrian regime,' Burt told Reuters in a telephone interview.

A report published by Human Rights Watch on Thursday, based on interviews with dozens of Syrian defectors, said army commanders had ordered troops to use 'all means necessary' to halt protests, often giving explicit instructions to open fire.

A sniper in Homs said his commanders ordered that a specific percentage of demonstrators should die. 'For 5,000 protesters, for example, the target would be 15 to 20 people,' he told Human Rights Watch (HRW).

HRW identified 74 commanders who had ordered, authorised or condoned killings, torture and unlawful arrests during the anti-government protests.

'These abuses constitute crimes against humanity,' it said, calling on the United Nations Security Council to refer Syria to the International Criminal Court.-Reuters