At least five people have been killed in a bomb attack in the Syrian city of Aleppo.

The British-based Syrian Observatory for Humans Rights said the blast wrecked a car wash in Tal al-Zarazeer, one of the poorest suburbs of the city.

Two blasts hit a highway in the capital Damascus, but no casualties were reported.

Reports from Syria cannot be independently verified due to restrictions on foreign media.

The bombings dealt another blow to a crumbling UN-backed truce.

50 out of a planned total of 300 United Nations observers are now in Syria to monitor the ceasefire declared on 12 April, but their presence has not halted the violence.

Activists said at least 37 people were killed yesterday when security forces fired on protesters around the country.

President Bashar al-Assad has argued that he is combating foreign-backed "armed terrorist groups" rather than a popular uprising.

Syrian officials say rebels have killed more than 2,600 soldiers and police.

The United Nations estimates that the security forces have killed more than 9,000 people since the rebellion began.