A plane downed in Sudan's North Darfur state had Russian crew members and was being used by the army to resupply the besieged city of al-Fashir, according to the opposing faction and documents it said were found in the wreckage, Paralel.Az reports citing Reuters.

The incident offers a glimpse into the murky supply networks behind the more than 18-month war between Sudan's army and the Rapid Support Forces (RSF) that has uprooted more than 11 million people, caused widespread hunger and drawn in foreign powers.

Flight tracking data and information from social media accounts that have not been previously reported suggest the transport plane switched months ago from supplying the RSF to the army. A Reuters analysis of the documents, footage and social media indicate at least one of the Russian crew had a past in arms trafficking.

Officials from the RSF shared footage showing its troops standing around the burning wreckage of the plane which they said they had shot down in al-Malha, north of al-Fashir, in the early hours of Monday.

In rare details on foreign involvement near front lines, the RSF also shared pictures purporting to show identity documents of two Russians they said were on board, along with three Sudanese army personnel.

An RSF source later said the aircraft was an Ilyushin transport plane used to carry out air drops of weapons, ammunition and provisions for al-Fashir, where the army and allied former rebel groups have been trying for months to fend off RSF attacks.

It had just made a delivery when hit, the source said.

Remnants of the plane's engine and stabilizer components match those of a Russian-made Ilyushin IL76 cargo plane, according to an analysis of the videos by the London-based Centre for Information Resilience, a non-profit group, which located the crash site 80 miles north of al-Fashir.

Reuters was able to confirm the location of the videos by the shape of the mountains, terrain layout and vegetation.

Sudan's army did not respond to requests for comment about the plane. Reuters could not independently confirm how the plane had been downed or what route it was flying.

Reuters identified at least two Russians thought to have been on board the plane by matching footage shared by the RSF of their IDs with social media profiles. Reuters used public databases of leaked personal data, facial recognition searches, and access to an official Russian database to confirm the identity of the suspected crew members.

Russia's embassy in Sudan has said it is investigating the incident. The Russian foreign ministry did not immediately respond to a request for comment. The Sudanese military is known to have commonly employed crews from ex-Soviet countries.