"A special saboteur unit, consisting of 300-500 members of radical nationalist organizations, has been formed in the Lviv region," Eduard Basurin told reporters in Donetsk.
Basurin said the members of the unit were expected to be deployed in the Stanichno-Luhansk district to carry out provocations while posing as Russian soldiers. He added that the provocations would most likely coincide with Victory Day celebrations.
Kiev and Donbass have been in the state of conflict since April 2014 when Kiev authorities launched a military operation in the country's southeast, fighting independence supporters in the region.
In mid-February, the warring sides agreed to a ceasefire deal, worked out by the leaders of Russia, Ukraine, France and Germany in Minsk, Belarus. The parties agreed to stop hostilities and withdraw artillery from the line of contact, but since that time both parties have reported truce violations.