Hayat Tahrir al-Sham (HTS) made the claim through the affiliated media channel Ibaa, but it did not mention the fate of the warplane's pilot.
"We were able to bring down the Russian warplane with a shoulder-fired missile above Saraqib in Idlib this afternoon," said Mahmoud al-Turkmani, who according to the statement heads the alliance's "air defence brigade."
HTS controls Idlib province and is dominated by fighters from Al-Qaeda's former Syrian affiliate.
The Russian defence ministry confirmed the Su-25 aircraft was shot down over Idlib province and said the pilot was killed "in fighting against terrorists."
"A Russian Su-25 aircraft crashed during a flight over the Idlib de-escalation zone. The pilot had enough time to announce he had ejected into the zone," the defence ministry said.
It added that "according to preliminary reports, the plane was shot down by a portable anti-aircraft missile system."
Troops loyal to Syrian President Bashar al-Assad launched a fierce offensive on Idlib in late December, with backing by Russian warplanes.
The Syrian Observatory for Human Rights also claimed the pilot was killed as he clashed with the anti-government fighters who had shot down his plane.
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