Moscow: A confrontation seemed certain as Kiev threatened to block a convoy of 262 Russian trucks rolling towards the Ukrainian border. Ukranian officials fear the convoy is a ploy to bolster pro-Kremlin rebels on its eastern territory.

The convoy of what Russia says is humanitarian aid has sparked fears of an escalation in a conflict that has left hundreds dead in eastern Ukraine in recent months and plunged Moscow's ties with the West to their lowest point in decades.

A convoy of Russian trucks passes along Don highway towards Ukraine. Credit:AP

France warned that Russia could use the operation as "a cover" for sending in troops, echoing earlier concerns from Canberra, Washington, Berlin and London.

Kiev said the trucks would be stopped at the border for any aid to be unloaded and transported into conflict-torn eastern Ukraine with the help of the Red Cross.