Syrian government forces have used fighter jets to bomb opposition strongholds in the northern city of Aleppo and suburbs of Damascus.

Both the BBC in Aleppo and ITN in the Damascus suburb of Douma have broadcast footage of the attacks.

Aleppo, Syria’s second most populous city has been the scene of fighting for almost a week. So far the air campaign has been supplemented with shelling, but has not been followed up with a ground assault.

According to the UK-based Syrian Observatory for Human Rights, the shelling in Aleppo has resulted in the killing of at least 26 people.

The UN has withdrawn half its 300 observers from the country, according to Herve Ladsous, the UN’s head of peacekeeping operations in Damascus.

Without a significant reduction in violence, the remaining 150 observers are expected to be pulled out after the expiry of the latest 30-day extension of the mission’s mandate agreed by the UN Security Council on July 20.