KYIV, June 1 - The jailed head of RIA Novosti-Ukraine, Kirill Vyshinsky, has appealed to both the Russian and Ukrainian presidents for help in his case and declared that he has given up his Ukrainian citizenship, RFE/RL reported.

Vyshinsky said on Friday in a court in the southern city of Kherson that he wanted Putin to take "all necessary measures for my immediate release" and for Russia to provide him with legal aid.

Vyshinsky, who received a Russian passport in 2015, was arrested two weeks ago and charged with high treason. He rejects the charges against him and was in court for a hearing on an appeal of his arrest.

"I appeal [for help] to [Ukrainian] President [Petro] Poroshenko, whom I know personally and with whom we have done several good deeds," he said. "I declare my withdrawal from my Ukrainian citizenship -- from this moment I consider myself only a citizen of Russia."

Vyshinsky also called for an "immediate" end to what he called the "persecution" of his family members and friends and appealed to Ukrainian Human Rights Commissioner Lyudmila Denysova to take note of his case.

"What is happening here and with me now is a gross violation of human rights," he said.

He said his arrest is a "political order" and suggested that he was arrested in order to use him in a swap with Moscow for a Ukrainian being held in Russia.

The Ukrainian Security Service (SBU) carried out a large-scale operation against RIA Novosti-Ukraine's staff members -- both at their offices and in several of their apartments -- and detained Vyshinsky outside his home.

The SBU said in a statement afterward that "a network of media structures, which Moscow used for carrying out a hybrid war" against Ukraine, had been uncovered.

The SBU said Vyshinsky was preparing reports at Moscow's request that sought to justify the annexation of Ukraine's Crimean Peninsula by Russia in 2014.

It said he was receiving some 53,000 euros (about $60,000) a month from Russian sources for his work, and that the money was sent to him through Serbia.

Vyshinsky faces up to 15 years in prison if found guilty of the charges against him. (rfe/ez)