Updated

A Ukrainian court has ordered a government official accused of spying for Russia to remain in custody during an investigation.

The court in the Ukrainian capital of Kiev ruled Friday that Stanislav Yezhov would be kept in jail through Feb. 17. His defense lawyer says Yezhov pleaded not guilty to the charges.

Ukrainian media reports identified Yezhov as a senior aide and personal interpreter to Prime Minister Volodymyr Groysman. He was arrested Wednesday.

Ukraine's Security Service, or SBU, alleges that Yezhov passed government secrets to Russian handlers.

Groysman told lawmakers that the aide, who accompanied the prime minister on foreign trips, was under SBU surveillance and without access to confidential information for some time.

Russia and Ukraine have been in a tug-of-war following Moscow's 2014 annexation of Crimea.