MOSCOW, Aug 13, 2014 (BSS/AFP) - A convoy of 262 Russian trucks was expected at the Ukrainian border on Wednesday as Kiev vowed to block the aid mission from its territory over fears it was a ploy to bolster pro-Kremlin rebels.

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.

The United States backed Ukraine's demand for border checks to clear up concerns that Moscow is seeking to support rebels.