BEIRUT (Reuters) - The Syrian army and its allies have captured the main water pumping station that supplies Aleppo in a sweeping advance against Islamic State that has brought them to the bank of the Euphrates, a group that monitors the conflict said on Tuesday.

The Syrian Observatory for Human Rights said the army and allied forces made rapid gains east of Aleppo city, as Syrian and Russian planes pounded the rural areas.

They recaptured the al-Khafsa area on the western bank of the Euphrates River, where the water treatment and pumping plants are located, after the jihadist group withdrew the Observatory said.

A Syrian military source had said earlier on Tuesday that the army had advanced to areas “very close” to both.

Aleppo’s main water supply has been cut off for nearly two months, and the city’s residents now rely mainly on ground wells or water purchased from private vendors.

A military media unit run by Hezbollah, a Lebanese ally which is fighting alongside President Bashar al-Assad’s government forces, also quoted a military source as saying the army had advanced and regained the al-Khafsa area.

Islamic State is losing ground in northern Syria to three separate campaigns - by the Russian-backed Syrian army, by U.S-backed Syrian militias, and by Turkey and allied Syrian rebel groups.

Aleppo was Syria’s most populous city before the war began nearly six years ago and has been entirely in government hands since December when the last rebel enclave in its eastern districts was overrun following months of intense fighting.