Doubts remain as Syria ceasefire comes into force

The deadline has passed for a ceasefire in Syria to come into effect as part of a peace plan proposed by the UN-Arab League peace envoy, Kofi Annan, but Western leaders have already expressed doubts about whether the Syrian government will honour the deal.

The Syrian government told Kofi Annan in a letter that it would halt all fighting by Thursday morning but reserved the right to respond to any attack by "armed terrorist groups".

Since rebels, loosely organised across Syria's provinces, do not obey a set chain of command, there is no guarantee they will obey the ceasefire either.

So far there have been no reported violations, but the US said Syria's pledge had "little if any credibility". The main armed rebel group said it would respond to any government attack.

Annan received written assurances from the Syrian foreign ministry that government troops would "cease all military fighting throughout Syrian territory as of 06:00... while reserving the right to respond proportionately to any attacks carried out by armed terrorist groups", his spokesman, Ahmad Fawzi said.

"An hour after the ultimatum expired, the situation is calm in all regions," Rami Abdel Rahman, chairman of the London-based Syrian Human Rights Observatory said.

If the ceasefire does hold, the focus is expected to fall on the withdrawal of government troops, tanks and heavy weaponry.

US President Barack Obama and German Chancellor Angela Merkel agreed in a telephone call on Wednesday that "more resolute" UN Security Council action was needed on Syria, the White House said.

But Russia - one of Syria's closest allies - said the rebels must respond with their own ceasefire.

US Secretary of State Hillary Clinton will meet her Russian counterpart Sergei Lavrov in Washington DC on Thursday during a G8 foreign ministers summit.

Any further action would need the agreement of Russia and China, who have already vetoed two Security Council resolutions on Syria.

Annan is due to brief the UN Security Council later on Thursday.

The UN estimates about 9,000 people have died since anti-government protests began in March 2011. In February, the Syrian government put the death toll at 3,838 - 2,493 civilians and 1,345 security forces personnel.