The United States and the United Kingdom are concerned about the decision of the Russian court, which sentenced Ukrainian political prisoner Pavlo Hryb to six years in prison, and urge Moscow to immediately release the Ukrainian.

"We are deeply concerned about today's Russian court decision unjustly sentencing Pavlo Hryb to six years in a penal colony. We are also concerned about Hryb's precarious health situation," the U.S. Embassy to Ukraine said on Twitter on Friday.

The U.S. calls on Russia "to release all political prisoners immediately, to respect Ukraine's sovereignty and the rights of its citizens, and to cease its baseless political persecutions of Ukrainians."

Jeremy Hunt, UK's Secretary of State for Foreign and Commonwealth Affairs, also called on Russia to immediately release Hryb.

"Russia's continued use of politically motivated detentions is appalling. Pavlo Hryb was today sentenced to 6 yrs. He is suffering from serious medical conditions & has not received adequate care in Russian detention. I echo @pavloklimkin & call for his immediate release #FreeHryb," Hunt wrote on Twitter.

Pavlo Hryb was detained while visiting Belarus on August 24, 2017. He was 19 at the time. It emerged later that he was held at a pretrial detention facility in Russia's Krasnodar. Russia accused Hryb of instigation of terrorism. He has denied any wrongdoing.

The North Caucasus Military District Court sentenced Hryb to six years in a general security penitentiary on Friday. Hryb said in his last plea that he did not admit the charges of facilitating terrorist activities.

Due to deteriorating health, Hryb needs urgent medical care, including surgery.