A man walks past the aftermath of an air strike by pro-Assad forces in Aleppo

Four top rebel commanders in Syria have switched sides to join President Assad’s forces in a further sign of disarray in fragmenting opposition ranks.

The men, from the Free Syrian Army (FSA), are thought to have become disillusioned with an opposition that is becoming increasingly dominated by Islamist factions and alliances. Islamists have been doing much of the recent fighting. There is also a strong sense that the recent gains made by Assad’s forces make it pragmatic for FSA officers to go back to the regime.

The defections are expected to improve Mr Assad’s standing in the June presidential elections.

Brigadier Mohammed Abu Zaid, the former president of the military court in Aleppo, Colonel Marwan Nahila, the head of the military council in Homs, and