Footage circulating on Twitter allegedly shows the burning Su-25 plane plunging to the ground. However, they claimed that the pilot died after ejecting by parachute, the TASS news agency reported, denying rebels claims that a pilot was captured.
There is no immediate word from Moscow to confirm the downing of the plane or the killing of the pilot.
He could not immediately confirm which faction had downed the plane but the militant Hayat Tahrir al-Sham (HTS) and other terrorist groups are active in Idlib.
The attack took place when the jet was flying over the Idlib de-escalation zone on Saturday. The Russian statement said the area was controlled by Jabhat al-Nusra militants. A Free Syrian Army fighter in the area told the source that the pilot "engaged with FSA fighters with a pistol but they killed him eventually".
Syrian soldiers and Iranian-backed militiamen were now around 12 kilometres from Saraqeb, advancing towards the Damascus-Aleppo highway under cover of heavy Russian air strikes, two opposition sources said.
The Idlib Media Center, an anti-government activist group, posted images that purportedly show the plane's wreckage. One of the armed men shouts: "He is Russian".
The pilot was later named on social media as Major Roman Filipov.
Russian Federation is a key ally of President Bashar al-Assad, and has been waging a military campaign on behalf of his forces since 2015.
Syria is in the process of carrying out an offensive against Islamist rebels in Idlib Province, where most of such groups are operating.
'There have been dozens of Russian air strikes in the area over the past 24 hours.
A Russian warplane was shot down Saturday in Syria, according to Russian state-run news agencies.
In August 2016, a Russian military helicopter was shot down over Syria and all five people on board were killed.
Russian Federation has been conducting military operations in support of Syrian President Bashar al-Assad since September 2015.