Previously, 20 more people investigated in the same case were placed under preventive arrest.
On Wednesday, organized crime prosecutors detained the accused for 24 hours and asked the court to issue 29-day preventive arrest warrants on their name.
The 39 people are accused of having caused losses to the state budget of over EUR40 million yearly between 2010 and 2012.
The preventive arrest decisions may be challenged with the Bucharest Court of Appeals.
On Tuesday prosecutors heard over 120 people in this case.