Ukraine's State Border Service is spotting vessels under the flag of Russia near drilling rigs on the Odesa and Holitsynske gas fields in the territorial sea of Ukraine.

The press service of the Border Service reported on Wednesday that when monitoring the sea surface from air the Diamond border aircraft monitored almost 2,600 square kilometers of the Ukrainian sea surface and ships and boats patrolled the northern part of the zone.

"Measures to monitor the situation on the Odesa and Holitsynske gas fields are being taken where platforms, drilling rigs and vessels under flag of Russia were seen," the authority said.

As reported, on July 25 employees of the State Border Service of Ukraine when monitoring the sea surface from air registered Russian self-elevating drilling offshore platforms, fixed platforms and supply vessels in Odesa and Holitsynske gas fields.