Explosions have struck two cities in Syria, with reports of at least five people dead, a day after a spokesman for Kofi Annan, the UN-Arab League envoy, said the UN peace plan for Syria remained on track.

The UK-based Syrian Observatory for Human Rights reported that five people were killed in a blast in Aleppo on Saturday, but gave no further details.

Earlier, on the central Damascus highway of Sharia al-Thawra, a bomb attached to a military vehicle caused destruction to nearby cars and buildings, but there were no reports of casualties.

The blast shook the neighbourhood near a military food co-operative, destroying nine cars and leaving a crater in the street, according to a reporter from the AP news agency who visited the scene.