The Syrian army and its allies, backed by Russian air power, are keeping up a heavy bombardment of insurgent positions in and around Aleppo, rebels said on Monday, pressing to complete their recapture of the city¡¯s strategic southern gateway.

After reimposing a siege on rebel-held eastern Aleppo with an advance in the city¡¯s southwest on Sunday, the army and its allies now aim to block the insurgents from bringing in reinforcements, a Syrian military source said.

The city, Syria¡¯s largest before the war, has become the most important front for both Syrian President Bashar Assad and his allies and for the rebels seeking to bring him down.