Ukraine accused its neighbor Russia on Friday of escalating the fighting in the Donbas region where pro-Russian separatists held an election last week that they say showed popular support for independence from Ukraine.

An Ukrainian military spokesman said a column of 32 Russian tanks, sixteen artillery guns and thirty trucks carrying ammunition and troops had crossed the border into southeastern Ukraine. NATO reported an increase in Russian equipment and troops along the Ukrainian border but could not yet confirm that tanks had entered the country.

Russia previously sent tanks and troops into Ukraine when the rebels fighting in the areas around the cities of Donetsk and Luhansk appeared on the verge of being defeated by Ukraine’s army. Russian support gave the separatists the upper hand and the military situation in southeast Ukraine had seemed at a stalemate since.

Russia has consistently denied arming the rebels after it occupied and annexed the Crimean Peninsula from Ukraine in March.

It did not reject the latest Ukrainian accusations outright on Friday but the Russian Foreign Ministry blamed the former Soviet satellite state for violating a ceasefire that was agreed to in Belarus’ capital Minsk last month. “In place of deescalation, Kiev has intensified the hostilities in the southeast of the country with the use of heavy equipment, which has led to thousands of casualties and large-scale destruction,” it said.

The deputy prime minister of the self-declared Donetsk People’s Republic also said Ukraine’s forces that launched a new offensive. “We are being attacked,” he said. “A full-scale war is going on now.”

The government in Kiev, which won a strong mandate in parliamentary elections in late October for its resistance to Russian attempts to divide the country, said the rebels had violated the Minsk accord by calling their own election.