Ten men suspected of using the digital currency Bitcoin to launder up to 20 million euros of criminal money made from online drug deals have been arrested in the Netherlands, Dutch prosecutors said on Wednesday.

The men, described as all in their 20s and with Dutch nationality, were arrested on Tuesday in coordinated raids on 15 locations around the country, said spokeswoman Valentine Hoen of the country's Fiscal Information and Investigation Service.

Prosecutors believe the men laundered 15-20 million euros ($16-22 million) for drug dealers who sold their wares at online marketplaces on the "Dark Web" -- web sites that are invisible to search engines and only reachable using specialized software.

Bitcoin is the preferred means of payment on such sites because it can be quickly transferred between users in any country without using a bank, making it difficult to trace.

Hoen said the actual drug sellers were the subject of a continuing investigation by the country's drug squad, although 15 kilograms of chemical precursors for the manufacture of Ecstasy were found in raids on Tuesday.

A statement by prosecutors said investigators seized luxury cars, cash, bank accounts and other goods abroad including an unknown amount of Bitcoin in cooperation with officials in the United States, Australia, Lithuania and Morocco.

According to an account in De Telegraaf newspaper, which was invited to witness the raids, the men were caught due to large amounts of money being frequently deposited into their bank accounts and then quickly withdrawn in cash from ATMs.

In all more than 250 law enforcement officials participated in Tuesday's raids.

Hoen said a judge in Rotterdam will rule on the suspects' continued detention on Friday.