Lubkivskyi noted that "the figure of 150 prisoners, held by the militants, is not final."
The SBU Head Adviser said that it is important for Ukraine to return all the Ukrainian citizens held by the militants.
He noted that the Minsk talks have not yet been completed and it is too early to speak about final achievement of any arrangements.
Representative of the 'DPR' terrorist organization Alexander Zakharchenko said Thursday that it was possible to reach an agreement with the authorities of Ukraine on large-scale prisoner exchange.
"We have removed the obstacles preventing prisoners' exchange. We will exchange 150 for 225," he told the reporters in Donetsk.
Chief of Investigation Department of the Security Service of Ukraine Vasyl Vovk said earlier last week: "We are anticipating the meeting in Minsk. Everything will be clear after the Minsk meeting. We want to exchange prisoners 'all for all.' The terrorists have to release all our illegally detained persons. We have counted 684 of them."
Vovk said that the SBU is ready to make a procedural finding to set all the "terrorists' associates" free but "those with blood on their hands, will not be released so far."