The latest version of the online black market Silk Road 2.0 and hundreds of other sites operating on the Tor network have been shut down as part of an international operation.
An estimated 400 websites have been shut down as part of a joint effort between 16 European countries and the US. 17 people have been arrested as part of the investigation.
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Tor houses thousands of illegal markets, often trading in drugs or child abuse images, but the anonymity that the network provides often makes it difficult for law enforcement to intervene effectively.
Blake Benthall, alleged to be behind Silk Road 2.0, has been arrested as part of the operation, which has also seized approximately $1 million (£632,000) worth of bitcoins.
Troels Oerting, head of Europol's cybercrime centre, told the BBC (opens in new tab)that the arrests were a breakthrough moment in the fight against dark net criminals.
"Today we have demonstrated that, together, we are able to efficiently remove vital criminal infrastructures that are supporting serious organised crime," he said.
"And we are not 'just' removing these services from the open Internet; this time we have also hit services on the dark net using Tor where, for a long time, criminals have considered themselves beyond reach."
The police raid required unprecedented levels of international co-operation, as well as the implementation of new technologies to locate dark net servers.
There are an estimated three million Tor users operating on the dark net, meaning that when the authorities shut down a site, copycat outlets often spring up immediately.
The Onion Router, or Tor, uses specially designed software to access parts of the Internet that would otherwise be inaccessible and utilises multiple layers of encryption to provide anonymity to users.
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Tor is also used by the military, journalists and members of the public living under autocratic regimes, but it is often associated with illegal activity.