Police have opened eight criminal proceedings connected to voting violations in Ukraine's presidential election, Interior Ministry Communications Department chief Artem Shevchenko has said.

"Currently, there are eight criminal proceedings… All polling stations are working as of 14:00," he said in Kyiv, adding that, as of 14:00, police have registered 522 complaints and reports of voting violations.

Ukraine is holding the first round of its presidential election on Sunday. The polling stations will close at 20:00. A record number - 39 candidates - are running in this presidential election.