After Russian servicemen blocked Ukrainian border units in Crimea, they destroyed video surveillance and communications systems, the State Border Service of Ukraine has reported.

"Russian riot police officers are setting up lines for holding negotiations, and for this reason the loss of mobile communications is predicted," reads the statement.

The service noted that earlier the Russian military had attacked the Kerch and Sevastopol naval guard detachments.

"After the seizure of the naval detachment there remained a small number of servicemen in the subunits. The rest of the personnel left the site on ships and motorboats, which were relocated. Under these difficult conditions border guards are deterring attackers and not letting them into weapons storage facilities," the service added.