Head of the Security Service of Ukraine Vasyl Hrytsak and all his deputies filed resignation reports.

"I fulfill my promise and publicly inform: today I am submitting to the newly elected President of Ukraine a report on my dismissal from the post of the head of the SBU," Hrytsak's statement published on the SBU website on Monday reads.

"I also inform you that, in accordance with the procedure established by the Military Regulations, the relevant dismissal reports were drawn up by all the deputy heads of the SBU and team members who side by side with me defended Ukraine during the most difficult days of the Russian armed aggression," Hrytsak added.

He added he "had written his resignation statement with a heavy heart."

"Just like everyone else, I am worried about the future of this service and the country and I can see pro-Russian revanchism raising its head in Ukraine. The current SBU staff will continue to ensure security of the people and state of Ukraine until the Ukrainian president and the Verkhovna Rada decide who will head the Ukrainian Security Service in the procedure prescribed by the Ukrainian Constitution," Hrytsak said.

Hrytsak was appointed acting head of the Ukrainian Security Service on June 8, 2015, and the Verkhovna Rada confirmed his appointment on June 8, 2015.