KYIV, Ukraine

Ukraine said Friday that those involved in controversial referendum in four Ukrainian regions will face criminal prosecution.

Kyiv's intelligence units have full information about the organizers and supporters of the "sham" referendums in Luhansk, Donetsk, Kherson and Zaporizhzhia regions, the Ministry for Reintegration of the Temporary Occupied Territories said in a statement.

The statement added that Ukraine will initiate criminal prosecution, suspend their social benefits and confiscate properties of those people.

The ministry also described them as "traitors" adding they could be sentenced to up to 15 years in prison.

Separatist-controlled Luhansk and Donetsk, as well as Kherson and Zaporizhzhia, which are partly under Russian control, announced plans for the referendums earlier this week.

The decision has been widely condemned by the international community, with European states and the US terming them "sham" referendums and saying they will not be recognized.

Voting will run from Friday to Tuesday in Luhansk, Donetsk, Kherson and Zaporizhzhia, with people asked to decide if they want these regions to become part of Russia.

Polls will be open from 8 a.m. (0500GMT) to 4 p.m. (1300GMT) in Luhansk, Zaporizhzhia and Kherson, while the closing time will be 8 p.m. (1700GMT) in Donetsk.

For security reasons, in-person voting will only take place on the last day, Sept. 27, while the other days will see ballots being organized in communities and conducted door-to-door, according to local media reports.