Syrian and Russian jets are stepping up strikes on opposition forces in northern Syria in retaliation for the sudden offensive that has cost the autocratic regime control of the country’s second largest city,

Syrian rebel fighters began preparations to seize Aleppo a year ago but the operation was delayed by war in Gaza and ultimately launched last week when a ceasefire took hold in Lebanon, the head of Syria's main opposition abroad told Reuters.

Russia has carried out air strikes on parts of the Syrian city of Aleppo after areas were seized by rebels opposed to the rule of President Bashar al-Assad. Recent days have seen the most significant offensive against the Syrian government in years and the withdrawal of its military from Aleppo,

Anti-government forces opposed to Syrian President Bashar Assad launched a shock attack on the largest city, Aleppo, on Saturday.