Ukraine's Security Service (SBU) on Tuesday conducted searches at the Kiev office of Russian news agency RIA Novosti.
Chief of the news agency's office Kirill Vyshinsky was detained, reported the Russian news agency TASS, citing a spokesperson for the SBU Elena Gitlyanskaya, as saying, in a statement.
According to the report, the SBU issued a statement announcing that "a network of media structures, which Moscow used for carrying out a hybrid war" against Kiev has been uncovered.
The move has drawn a response from Russia, with President Vladimir Putin's spokesman saying journalist Kirill Vyshinky's detention was "disgraceful and scandalous" if it was related to his work, according to several media reports.
"Tit-for-tat measures [after the detention of a staff member of Russian news agency in Kiev] will be certainly taken, but to say something more particularly we need to first get more detailed information," acting Kremlin Spokesperson Dmitry Peskov told reporters on Tuesday.
Kyiv has prohibited over a dozen Russian television channels since 2014, accusing them of spreading propaganda.