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.

The surprise attack jolted the frontlines of the Syrian civil war that have largely been frozen since 2020. The army said it was preparing a counteroffensive.

The Syrian government has been fighting back against opposition forces with airstrikes after they took over large swathes of land in a lighting advance which has caused embarrassment to President Bashar Al-Assad.

Russia appears to be "letting the Syrian rebels overthrow" President Bashar al-Assad according to Richard Grenell, who served as acting director of National Intelligence for a time during Donald Trump's first administration.

Russia has launched air strikes on parts of Aleppo - Syria's second largest city It comes as rebel forces have launched the largest offensive against the government in years earlier this week The surprise offensive prompted the first Russian strikes on the city since 2016,

The Syrian military said on Saturday that rebels had entered large parts of Aleppo city during an offensive in which dozens of soldiers had been killed, forcing the army to redeploy - the biggest challenge to President Bashar al-Assad in years.