About 150 people were arrested in one of the biggest global crackdowns on illegal trading on the dark web, Europol announced on Tuesday.
The DarkHunTOR operation was launched after the January dismantling by German police of DarkMarket, one of the leading cyber black marketplaces.
Since then, a series of "separate but complementary actions" were carried out in Australia, Bulgaria, France, Germany, Italy, the Netherlands, Switzerland, the United Kingdom and the United States", Europol said.
As a result, 65 people were arrested in the US, 47 in Germany, 24 in the UK, and four in Italy and the Netherlands each.
Several of those arrested were "high-value targets", Europol said.
The dark web is a collective of websites that are only accessible through a special web browser that encrypts the user's activity in order to keep it anonymous and private. This is why it is favoured by criminal networks.
Police also seized €26.7 million in cash and electronic currencies as well as drugs, including 25,000 ecstasy tablets, and 45 firearms.
In Italy, police also shut down illegal marketplaces called "DeepSea" and "Berlusconi" which between them had "more than 100,000 ads for illegal products", according to Europol, whose operation was coordinated with Eurojust, the European agency for judicial cooperation.
"The purpose of operations like this is to send a message to criminals operating on the dark web (that) the law enforcement community has the means and international partnerships to unmask them and hold them accountable for their illegal activities, even in dark web areas," Europol's deputy director of operations, Jean-Philippe Lecouffe, said.