A Ukrainian court has ordered the head of a major Russian state news agency's branch in Ukraine held for two months on charges of high treason in a case that drew angry criticism from Moscow and expressions of concern from media watchdogs.

The Kherson City Court in Ukraine’s south ruled on May 17 that the director of RIA Novosti Ukraine, Kirill Vyshinsky, be held until July 13 pending investigation of the charges against him.

Vyshinsky was detained in Kyiv on May 15 by the Ukrainian Security Service (SBU), and his apartment and the news outlet's office were searched. He was later transferred to Kherson.

The SBU accused RIA Novosti Ukraine of participating in a "hybrid information war" waged by Russia against Ukraine.

SBU officials said Vyshinsky, who has dual Russian-Ukrainian citizenship, received financial support from Russia via other media companies registered in Ukraine in order to disguise links between RIA Novosti Ukraine and Russian state media giant Rossia Segodnya.

The case has sparked a fresh dispute between Kyiv and Moscow, with the Russian Foreign Ministry calling Vyshinsky’s arrest an act of “blatant arbitrariness” and an attack on freedom of speech, the ministry said in a May 17 statement.

The OSCE's representative on freedom of the media, Harlem Desir, called on Ukrainian authorities to “refrain from imposing unnecessary limitations on the work of foreign journalists.”

The U.S. State Department said Washington shares Ukraine's concern about Russian propaganda but added that Ukraine must ensure it abides by the law, including international human rights law.

Tensions between Moscow and Kyiv have risen sharply since Russia seized Ukraine's Crimea region in 2014 and threw its support behind separatists in eastern Ukraine, helping start a war that has killed more than 10,300 people.

Ukraine's pro-Western government is wary of Russian media outlets, accusing Moscow of distributing disinformation aimed at sowing tension and destabilizing the country. Kyiv has banned more than a dozen Russian television channels since 2014, accusing them of spreading propaganda.

With reporting by RIA, UNIAN, TASS, AFP, AP, Interfax, and pravda.ua