The Russian occupiers have tasked substance abusers in the construction of fortifications in temporarily occupied Crimea, the General Staff of Ukraine has said.

"The Russian invaders involve the local population in the construction of fortifications in the settlements of Dzhankoi district in temporarily occupied Crimea," it said on Facebook on Friday.

According to the General Staff, mostly men, the majority of people involved in engineering works are drug and alcohol addicts.

The occupiers promise the workers to pay money, however, the people do not receive it at all or are paid less than had been promised.

"There are cases when the deceived people refuse to cooperate further, after which the armed occupiers force them to dig trenches," it said.