Dutch police said on Thursday they have shut down and dismantled one of the biggest ‘illegal market places on the internet today’ after keeping it running for a month and recording thousands of transactions.

Hansa Market was the most popular dark market on the ‘anonymous’ part of the internet, or dark net, police said in a statement.

The international investigation was carried out together with Europol, the FBI and the authorities in Germany and Lithuania. This week a Dutch seller was arrested in Krimpen aan den Ijssel and his accounts, with some €2m in bitcoins were seized.

Police say the winding up of Hansa Market is the final step in an undercover operation which began when Dutch police seized control of the illegal market place on June 20 after two of the site’s administrator were arrested in Germany.

The website was hosted on servers in Lithuania. Once the administrators were arrested, the servers and infrastructure were sequestered and transferred to Dutch servers, allowing the police and public prosecution department to monitor all trades.

Drugs

Most of the trades were involved drugs, police said. On average, 1,000 orders per day were placed in response to almost 40,000 advertisement sand more than 50,000 transactions have been monitored since the authorities took control of the website.

Some 10,000 foreign addresses of Hansa Market buyers were passed on to Europol and more than 500 Dutch delivery addresses were reported to couriers and postal services so they could halt deliveries, police said.

Dark net markets enable large-scale trading in chiefly illegal goods, such as drugs, weapons, child pornography, and ransom software. Well-known examples include Silk Road (taken down by the FBI in 2013) and Alpha Bay (reportedly shut down earlier this month).

The police said that the number of transactions processed through Hansa Market rose from 1,000 to 8,000 after Alpha Bay was dismantled. No weapons or child pornography were sold on Hansa Market.