The OSCE said in a monitoring report that the Russian convoy consisted of seven fuel tankers, one truck, one other means of transport and one accompanying car. The truck bore the inscription "Humanitarian Assistance from the Russian Federation."

This was the fifth such “aid convoy” to cross into Ukraine from Russia since August, with a sixth reported to have crossed into Ukraine later. None of the convoys have been approved by the government in Kyiv.

The OSCE said it was able to inspect the convoy, opening the truck, but Ukrainian customs officers were not allowed to approach the vehicles, and were only able to examine them visually from behind a fence and take photographs

The OSCE’s report said the convoy crossed into Ukraine at 0750 Moscow time, and returned from Ukraine to Russia at 1320.

The report may fuel suspicions in Kyiv that the Russian aid convoys are being used by Russia to deliver fuel and ammunition to anti-government militants in the Donbas conflict zone. Military blogger Dmytro Tymchuk said on Wednesday that militant attacks on Ukrainian forces had intensified after the latest visits by Russia’s aid convoys, which he said had resupplied the militants and Russian mercenaries in the Donbas.

VIDEO: OSCE: Russian convoy which illegally entered eastern Ukraine consisted of seven fuel tankers.