The tanks entered Ukraine along with other armour through a checkpoint controlled by rebels in the Luhansk region, Arsen Avakov said.

The army engaged two of them and destroyed part of the column, he said.

Meanwhile, the Russian and Ukrainian presidents have discussed plans to defuse the crisis, reports say.

Vladimir Putin and Petro Poroshenko, who was elected last month, exchanged their views in a telephone conversation, Kremlin spokesman Dmitry Peskov was quoted as saying by Russia’s media.