Two of the largest "dark web" marketplaces for illegal items including guns and drugs have been shut down by the US government, the country's Justice Department has said.
AlphaBay and Hansa, two of the largest marketplaces on the Tor network, which helps users browse the internet anonymously, have been taken offline as the result of an investigation by the US, working with police in Europe.
Users of the dark web network buy illegal items, also including malware and stolen data, using digital currencies such as Bitcoin - transactions which are also harder to trace.
The anonymous nature of the dark web has seen large sections of it become an online black market.
According to the investigation, there were more than 250,000 listings on AlphaBay, as well as 200,000 members and 40,000 vendors.
Officers from Europol and the Dutch National Police Force worked with the FBI and Drug Enforcement Agency (DEA) in the US to complete the investigation and seizure of servers.
US attorney general Jeff Sessions said: "The dark net is not a place to hide. We will find you."
AlphaBay was first reported to have gone offline last month, sparking reports in some quarters that it had been the target of law enforcement action.
The site was widely regarded as the largest dark web marketplace for illicit items such as drugs, and was seen as the replacement for the infamous site Silk Road, which was shut down by the FBI in 2013.
The second marketplace, Hansa, was taken over by the Dutch National Police on June 20, with servers seized in Lithuania, the Netherlands and Germany. The Dutch authorities then monitored criminal activities on the site before it was shut down today.
Europol executive director Rob Wainwright said: "This is an outstanding success by authorities in Europe and the US.
"The capability of drug traffickers and other serious criminals around the world has taken a serious hit today after a highly sophisticated joint action in multiple countries.
"By acting together on a global basis the law enforcement community has sent a clear message that we have the means to identify criminality and strike back, even in areas of the dark web. There are more of these operations to come."