Saudi Arabia is in talks with Pakistan to provide anti-aircraft and anti-tank rockets to Syrian rebels to try to tip the balance in the war to overthrow President Bashar al-Assad, a Saudi source said Sunday.

The head of the Syrian opposition, Ahmad Jarba, promised during a flying visit to northern Syria last week that "powerful arms will be arriving soon."

The UN Security Council unanimously adopted a resolution Saturday calling for humanitarian aid convoys to be allowed access across war-torn Syria, but diplomats immediately voiced doubt about its effectiveness.

The text of the resolution 2139, which was the subject of fierce negotiations between Moscow and the West and condemns terror attacks in Syria, calls for "all parties to immediately lift the sieges of populated areas... and other locations."

UN Secretary-General Ban Ki-moon welcomed the move, but said the resolution "should not have been necessary."

"Some 200,000 people are under siege in government-controlled areas -- and 45,000 in opposition-controlled areas," he added.

On the ground, Syrian air forces shelled Syrian opposition strongholds in Yabroud, Aleppo and Daraa.

And at least 10 people killed and others injured in car bomb in Syrian border town of Atmeh between Idlib and Turkey.