The spokesman for the interior ministry, Krunoslav Borovec, confirmed Kolar's apprehension.
According to unofficial information, Kolar, a former long-standing HSS parliamentarian and head of the Molve municipality, is suspected of HRK 2 million embezzlement.
He was at the helm of that municipality until the last local election when Stjepan Fosic of the Croatian Democratic Union (HDZ) won the polls.
Later in the day at a news conference in the eastern town of Djakovo, HSS leader Josip Friscic said the ruling coalition agreed on zero tolerance to abuse of office, corruption and crime.
He announced that the presidency would likely suspend Kolar next week.