Ukraine will unilaterally hand over 15 people, who were detained and sentenced in Ukraine, to promote to the process of hostages' swap, SBU chief Vasyl Hrytsak has said.

"Now we will give 15 people back on a unilateral basis who have already received their sentences at courts. We will just hand them over to break the deadlock," Hrytsak said in an interview with 112.Ukraine TV channel on Sunday night.

"The decision on the hostages' swap is taken by one person alone [in Russia]. We are ready to do anything to take away our guys," he said, recalling that there are 109 Ukrainian citizens held captive.