US-BACKED insurgents have fired chemical weapons into Syria’s largest city Aleppo, Russia’s Defence Ministry said yesterday.

Spokesman Major General Igor Konashenkov said Russian military experts had “found evidence of chemical weapon use by terrorists against the civilian population and Syrian servicemen.”

The investigators, who arrived last week, found a “high probability” of toxic chlorine gas and white phosphorous in unexploded shells and soil samples from south-western districts of the city, including the 1070 housing estate.

The 1070 area was finally wrested from the Army of Conquest, an alliance of al-Qaida affiliate the Levant Conquest Front and the US-backed Ahrar as-Sham and Army of Islam, on Tuesday.

That victory was a major setback for the insurgents’ three-week offensive to capture all of Aleppo and rescue some 2,000 of their cohorts trapped in the city’s east.

“Militants, who have been striving in the past days to break though the Syrian army’s exterior defence ring of Aleppo at any cost, have used toxic substances multiple times,” Gen Konashenkov said.

Yesterday, the Syrian army and its Lebanese Hezbollah allies recaptured parts of the al-Assad and Minyan districts lost during the offensive.

But the arrival of massive militant reinforcements halted their advance.

Meanwhile, warplanes from Russian aircraft carrier the Admiral Kuznetsov began reconnaissance flights over Syria in preparation for a new campaign of air strikes.

On Thursday, United Nations special adviser on Syria Jan Egeland warned that food supplies in east Aleppo would run out next week.

Gen Konashenkov said he had received a request from the UN to call further “humanitarian pauses” there, although each previous one has been rejected by the surrounded insurgents, who refuse to let civilians leave.

“Every time it seems to be just another effort to find an excuse for disrupting the UN humanitarian aid delivery to the residents of Aleppo,” he said, pointing out that his country had delivered more than 100 tons of aid to the city in recent months.

The Syrian Foreign Ministry said the militants’ response showed the “terrorist nature” of groups backed by US allies Turkey, Qatar and Saudi Arabia.

Kremlin spokesman Dmitry Peskov blamed Washington’s failure to “disentangle the so-called moderate opposition … from terrorist groups” for the failure of efforts towards a peace deal for Syria.