At least 20 people have died after the Syrian army stormed Deir al-Zour, the largest city in the east and a scene of frequent protests, BBC reports.
Syrian rebels say the bombardment of Deir al-Zour began at dawn on Sunday, with scores of tanks and armoured personnel carriers moving into many parts of the city, to the sound of loud explosions and machine-gun fire.
Earlier, the UN Secretary General Ban Ki-moon told President Bashar al-Assad to stop using troops against civilian protesters.
