A Ukrainian court on Friday placed under arrest an aide to Ukraine's Prime Minister Volodymyr Groysman who is suspected of being a Russian spy, the country's SBU security service said.
Stanislav Yezhov, a top government interpreter, was detained two days before at his workplace and accused of high treason.
He "gathered information about government activities with special equipment" and passed it to his handlers, the SBU said in a statement on Wednesday.
Kiev's Shevchenkivskyi court during a hearing closed to the media ruled to put Yezhov under arrest for the time of the investigation, SBU said.
"The court has placed Yezhov in custody for two months at the request of the SBU," security agency spokeswoman Olena Gitlyanska told AFP by phone.
Yezhov is believed to have been recruited when he was working at Ukraine's embassy in Washington and had acted in Russia's interests for at least two years.
Photos on what appears to be his social networking profile on Russian website VK show him on trips with Groysman, including sat behind the prime minister during talks with former US vice president Joe Biden.
Yezhov is one of the more high-profile Ukrainian officials accused for working for Russia following the pro-European revolt in Ukraine which toppled the former pro-Moscow leader Yanukovych in February 2014.
The two countries became arch-foes following the subsequent annexation by Moscow of Ukraine's Crimean peninsula and the ongoing conflict in eastern Ukraine where pro-Russian separatists have declared independence.