The Security Service of Ukraine (SBU) is conducting searches on Monday at Kyiv and Odesa offices of Yandex.Ukraine, which is suspected of high treason.

"Within the framework of the criminal proceedings on high treason, searches are being conducted at the mentioned companies in Kyiv and Odesa," SBU spokesperson Olena Hitlianska told Interfax-Ukraine.

According to a report on the SBU website, the management of Yandex.Ukraine illegally collected, stored and transferred to Russia personal data of Ukrainian citizens, in particular data about their occupation, lifestyle, housing, residence, work, leisure, sources and amounts of income, telephone numbers, email addresses and accounts in social networks.

The special services discovered that the citizens, whose information was transmitted to Russia, included law enforcement and special forces officers, servicemen of the Armed Forces of Ukraine, other units participating in the anti-terrorist operation (ATO) in the east of Ukraine, and employees of state authorities and government.

"The information was then passed on to special services of the Russian Federation for planning, organizing and conducting reconnaissance, sabotage, information and subversive operations in our country to harm Ukraine's sovereignty, territorial integrity and inviolability," the website reported.

During the searches the SBU employees found server equipment and documents, which will be sent for examination. Experts will check if Yandex.Ukraine was collecting, accumulating and transferring personal data of Ukrainian citizens to Russia. They will also analyze the redirection of Ukrainian users' traffic to Russian servers, as well as check the coordination of unlawful activities from Russian territory.

The Yandex press service has confirmed the information on the searches conducted by the SBU in the Odesa and Kyiv offices of Yandex.Ukraine.

"We currently do not have information on the reasons for today's actions by the SBU. Attorneys are on their way to our offices. We are ready to provide the necessary information to the agencies using legal procedures," the press service said.

As reported, on May 16 Ukraine's President Petro Poroshenko signed a decree enacting a resolution by the National Security and Defense Council of Ukraine (NSDC) dated April 28, 2017 on the application of personal special economic and other restrictive measures (sanctions).

The Ukrainian president's decree imposing sanctions on the social networking sites VKontakte and Odnoklassniki, and also the companies Mail.ru, Yandex and their services took effect on Wednesday. User access to all Yandex and Mail.ru services has been banned for three years.