The Russian defence ministry confirmed the downing of an Su-25 and said the pilot was killed in fighting with "terrorists".
Idlib has always been the region where civilians and fighters have gone as they fled rebel-friendly areas under siege by the Syrian regime. Preliminary data showed the Su-25 plane was downed by a man-portable air-defense system (MANPAD), the ministry said in a statement on Saturday.
Militants shot down the plane in an area controlled by al-Nusra Front fighters, according to the RIA Novosti report.
The Syrian Observatory for Human Rights says the pilot was alive when he landed - but was killed after resisting capture by militants.
"On February 3, 2018, a Sukhoi 25 Russian fighter jet crashed when flying over the Idlib de-escalation zone".
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Video posted on social media appeared to show the plane being hit, while other video showed burning wreckage on the ground, with a red star on a wing. Residents said Russian warplanes were responsible.
Since then, Syrian government forces have captured wide parts of the country and in recent weeks have been marching in the rebel-held northwestern province of Idlib. The pilot managed to eject but was killed later while fighting against terrorists.
Syrian President Bashar al-Assad's regime recently resumed airstrikes on rebel-held areas such as Idlib province, prompting tens of thousands of civilians to flee their homes, according to United Nations officials. This plane was also carrying out raids there, ' said Abdel Rahman.
Russian Federation is a key ally of President Bashar Assad, and has been waging a military campaign on behalf of his forces since 2015.
The Ibaa News Agency of the al-Qaida-linked Levant Liberation Committee, said Russian and Syrian warplanes and helicopter gunships have been pounding Saraqeb and the village of Tel Mardeekh in Idlib since the early hours of Saturday. Two months later, Turkey shot down a Russian warplane. A third rebel source said he was killed. The UN said some 100,000 civilians have been displaced.