A security watchdog on Tuesday said for the first time it had spotted Russian-made weapons in rebel-held areas of eastern Ukraine, despite the Kremlin insisting it has not provided arms in the conflict.
The statement from the Organization for Security and Cooperation in Europe (OSCE) is a rare independent confirmation that sophisticated Russian-produced arms are involved in the fight between the Ukrainian army and separatists.
In a statement to AFP, the OSCE Special Monitoring Mission to Ukraine said that on July 28, it had "spotted four distinct electronic warfare systems ... in areas not controlled by the government."
The mission said one of its drones had seen the Leer-3, Krasukha-2, Bylina, and Repellent-1 systems some 64 kilometers (40 miles) south-west of the rebels' stronghold Luhansk.
The systems - designed to jam mobile communication and disable radar guided missiles - started being produced only a few years ago and are made in Russia.
The OSCE report did not explicitly name the country of origin.
Repellent-1 was designed to disable and destroy drones at distances of up to roughly 30 kilometers, according to Russian media.
The mission confirmed to AFP that its drones, which are used to monitor the four-year-old conflict, have been jammed dozens of times, but refused to speculate on the source of the interference.
More than 10,000 people have been killed since the conflict with Moscow-backed rebels broke out in April 2014 following Russia's annexation of Crimea from Ukraine.
Ukraine and its Western allies accuse Russia of funneling troops and arms across the border.
Moscow has denied the allegations despite overwhelming evidence that it has been involved in the fighting.
The OSCE team's 600 members are the only independent monitoring mission in the war-torn area.
They provide daily reports on the fighting and have drawn the insurgents' ire for accusing them of being responsible for most violations of a truce deal.