Some 35 volunteers are unloading the truck with the supplies of rice.
Some 30 trucks of the Russian humanitarian convoy crossed into Ukraine earlier on Saturday via a checkpoint in the Rostov Region where they previously cleared customs.
The Russian side has repeatedly invited Ukrainian customs officials and representatives of the International Committee of the Red Cross (ICRC) to inspect the cargo, but was turned down without explanation.
The third Russian humanitarian convoy comprises some 200 trucks that carry water, food, generators and medication to the eastern regions of Ukraine.
On August 22, the first Russian convoy with humanitarian aid that consisted of 280 trucks arrived in Luhansk after a series of delays. The second humanitarian convoy consisting of about 200 trucks arrived in eastern Ukraine last weekend, carrying cereals, sugar, tinned food, drinking water, medication and warm clothes, and safely returned to Russian.
The east of Ukraine suffered greatly as a result of the military confrontation between the Kiev-backed forces and independence supporters of eastern Ukraine that started in mid-April. The confrontation has claimed the lives of more than 3,000 people.
A ceasefire agreement was reached on September 5 at the Contact Group meeting on the settlement of the Ukrainian crisis in the Belarusian capital of Minsk. Despite the holding ceasefire, Kiev and independence fighters have accused each other of violating the ceasefire regime in the region.