I have enforced state rule so will stop fighting: Bashar al-Assad

Syria on Wednesday promised to honour a ceasefire due to come into force this morning despite accusations that the regime of President Bashar al-Assad was using it as an opportunity to inflict crushing blows on the opposition.

Kofi Annan, the United Nations envoy and architect of the ceasefire proposal, yesterday said he had received a promise from Assad's government that it would "cease all military fighting throughout Syrian territory" at 6am local time, in accordance with the plan.

Syrian state television read out a similar pledge. "After our armed forces completed successful operations in combating the criminal acts of the armed terrorist groups and enforced the state's rule over its territory, it has been decided to stop these operations from Thursday morning," it said.

World powers were last night discussing back-up plans for the crisis, with many assuming that the ceasefire would fail. David Cameron was due to speak to Annan, who must decide whether to call an end to his own six-point peace plan or allow it more time.

Activists said that the regime had used the build-up to the ceasefire, supposed to include a withdrawal of all troops from towns and cities, to make further raids, arresting activists and bombarding rebellious areas.

"We always knew this was the Assad plan," said one activist. "We would be forced to hold back while he carried on his attacks. We fell into his trap but we had no choice." Activists and video reports talked of shelling and other military action in Homs, Rastan, Deir al-Zour and other cities throughout the country.

On Tuesday, William Hague, the British Foreign Secretary, said he wanted the regime referred by the United Nations Security Council to the International Criminal Court. Yesterday, Cameron also urged the UN to take action.

"We estimate that 1,000 people have died in the last week, 300 over the Easter weekend," he said. "Far from fulfilling their commitments, the regime is cynically exploiting the window of diplomatic negotiations to crack down even harder on its own people. With increasing refugee flows across international borders, Assad's actions are now threatening regional peace and security."

There was no immediate sign that Russia and China, which both vetoed previous resolutions condemning Assad, had changed their position. But China issued a strongly worded call for Assad to abide by the ceasefire, to add to a Russian demand on Tuesday for him to act "more decisively".

"Violence and conflict in Syria still persists and the toll of civilian casualties is rising," a Chinese foreign ministry spokesman said. "China is deeply concerned about this." If Annan declares that Syria has failed to keep the ceasefire, it would put huge pressure on both nations to change their position. But he is more likely to ask for an extension.

Hillary Clinton, the US secretary of state, was due to meet her Russian counterpart, Sergei Lavrov, on the eve of a meeting of Group of Eight foreign ministers to press him to change Moscow's stance. Turkey's foreign minister, Ahmet Davutoglum, said he would address all G8 ministers by video conference.

Turkey is said to be considering creating a buffer zone for refugees which could become a base for armed opposition to the regime, even if its original intention were only to protect Turkish territory. Syrian troops fired over the border for the third day in a row, according to refugees in the Kilis camp nearby.

A member of the Free Syrian Army who called himself Omar said he had been shot by Syrian troops as he ventured into no-man's land between the two frontier posts to retrieve the body of a rebel.

If Annan says the ceasefire has been met, Britain and other Western powers will come under pressure to persuade the opposition to join talks with Assad, which they have vowed not to do. But they will also point out that as well as representing the UN, Annan is formally the envoy of the Arab League, whose demand that Assad hand over power to his deputy and hold free elections has not been withdrawn.