Kofi Annan, the special UN and Arab League envoy to Syria, said the regime in Damascus had accepted his plan for resolving the country’s crisis even as its tanks, troops and artillery pummelled opposition strongholds and crossed the border into Lebanon.

The former UN secretary-general conceded he faced a “l(fā)ong and difficult task” in ending the fighting but a spokesman for Mr Annan said Damascus had accepted the six-point peace plan, which the UN Security Council has endorsed and Mr Annan himself has called an “important initial step”.

As if to emphasise the task ahead, Syrian troops advanced into north Lebanon, destroying farm buildings and clashing with rebels holed up there, residents said. Neither President Bashar al-Assad nor his adjutants publicly endorsed Mr Annan’s plan and the Syrian leader even visited the Baba Amr district of the embattled city of Homs in an attempt to claim victory over the rebellious city.