Photo from UNIAN

On July 16-17, the jack-up-rig 'Sivash' was towed off the port Chornomorske (the temporarily occupied territory of Crimea) to the Holitsyno gas field, which is located in Ukraine's exclusive (maritime) economic zone, according to Ukraine Today.

Ukraine's State Border Service reported, it is the jack-up-rig (belonging to Ukrane's company Chornomornaftogaz) that was illegally seized by Russia during its annexation of Crimea in 2014.

"This is related to Russia's illegal offshore drilling operations in Ukraine, which grossly violates the UN Convention on the Law of the Sea and Ukraine's Law "On the exclusive (maritime) economic zone of Ukraine", said the statement.

Read alsoUkraine accumulates 10 bcm of gas in stockWhile observing the gas field, Ukrainian border guards spotted armed people near the drilling rigs and platforms. The State Border Service informed Ukrainian relative ministries and agencies on the incident.

Ukraine's Foreign Ministry is preparing an official note to be submitted to the Kremlin authorities.

Chornomornaftogaz is part of Naftogaz Ukraine and specializes in exploring and producing oil and gas in the Black and Azov Seas. In 2014, drilling rigs and other property of Chornomornaftogaz were seized during the Russian annexation of the Crimea. As a result, Naftogaz Ukraine has lost control of its Crimean enterprises.