AMMAN (Reuters) -Russian and Syrian warplanes targeted insurgents in an Aleppo city suburb on Saturday, two Syrian military sources said, after the rebel fighters penetrated the heart of the city in Syria's northwest in a surprise attack the previous day.

Russia's Defence Ministry said its air force had carried out strikes on Syrian rebels in support of the country's army, Russian news agencies reported on Saturday, amid an advance by forces opposed to Syrian President Bashar al-Assad.

The surprise attack, led by the Islamist group Hayat Tahrir al-Sham, was the boldest rebel assault for years in the civil war that has been frozen.