"Representatives of the Security Service of Ukraine are now in our offices in Kyiv and Odesa. We do not yet have information about the reasons for today's SBU operation. Lawyers are now heading to our offices. We are ready to provide required information to the authorities in the framework of legal procedures," AIN.UA quoted Melkumova as saying.

SBU press secretary Olena Hitlyanska has also confirmed information that the SBU came to search Yandex's Ukrainian offices. According to her, the search is conducted under Article 111 of the Criminal Code of Ukraine – high treason.

Read alsoNATO chief comments on Ukraine's ban of Russian social networksAs UNIAN reported earlier, Ukrainian President Petro Poroshenko signed a decree greenlighting a new set of sanctions against Russia, which include blocking access to Russian-based social networks VKontakte and Odnoklassniki, as well as Yandex online services. The initiator of the Yandex ban was the Security Service of Ukraine.

On May 17, the presidential decree came into force.

On May 18, Yandex's accounts were blocked in Ukraine.