"Several explosive devices detonated as a convoy of minibuses drove past and nine passengers of one of the buses were killed," said Observatory director Rami Abdel Rahman.

He said the blasts occurred on the road linking Homs city to a string of villages populated by Alawites, an offshoot of Shiite Islam to which President Bashar al-Assad belongs. Other four people were also injured in the attack.

Earlier on Tuesday, another car bomb exploded on the Syrian side of the main Bab al-Hawa border crossing with Turkey, killing at least seven people and wounding 20, the Turkish news agency Dogan said.

The explosion occurred at a roadblock manned by militants at the entrance of the rebel-held crossing, several hundred meters from the Turkish side, activists said.

The wounded were rushed to Turkish hospitals. Dogan reported seven people killed – a figure unconfirmed by the Turkish foreign ministry.

Pictures taken by activists at the scene showed several burnt and mangled cars.

NJF/NJF