U.S. authorities working with law enforcement officials abroad have shut down the Darkode online forum used by cybercriminals around the world and charged 12 people linked to the site, the Justice Department said on Wednesday.

U.S. Attorney David Hickton announced the charges in Pittsburgh and called Darkode “a cyber hornet's nest of criminal hackers.”

“Of the roughly 800 criminal Internet forums worldwide, Darkode represented one of the gravest threats to the integrity of data on computers in the United States,” he said.

The Federal Bureau of Investigation and U.S. attorney's office in Pittsburgh led the investigation, known as Operation Shrouded Horizon. It included authorities from Europol and 20 countries in Europe and Latin America as well as Israel, Nigeria and Australia.

The Justice Department said 12 people were charged, mostly in the United States, in what it called the largest coordinated international law enforcement effort ever directed at an online cybercriminal forum.

Europol said there had been 28 arrests.

The investigation is continuing as authorities look into a total of 70 Darkode members and associates worldwide, the Justice Department said.

Cybercriminals used Darkode to trade stolen data as well as hacking and spam tools and services, and methods for cyberattacks on governments and companies. It was an invitation-only website, hidden by well-protected Internet servers.

The darkode.com website on Wednesday showed logos of various law enforcement agencies and a notice saying the domain had been seized by the FBI as part of an investigation with international agencies.

“Darkode was unusual because it was a virtual crossroads for criminal hackers from a variety of languages, countries and backgrounds,” said Brian Krebs, who writes about cybercrime on krebsonsecurity.com and had infiltrated the forum in order to study it.

“For many years, some of the most accomplished cybercriminals sold their wares and services on this forum, including everything from denial-of-service attacks for hire to malicious software and stolen identities and credit cards.”

Among those charged was Johan Anders Gudmunds of Sollebrunn, Sweden, known as Synthet!c, whom the Justice Department said was Darkode's administrator. Daniel Placek, 27, of Glendale, Wisconsin, and Matjaz Skorjanc, of Maribor, Slovenia, were also among those arrested. Placek and Skorjanc allegedly created Darkode in 2007 “for the purpose of bringing together the most talented computer hackers and cybercriminals on the Internet,” court documents said.

Skorjanc is jailed in Slovenia and must be brought to Pittsburgh to face charges, including racketeering, conspiracy and wire, bank and computer fraud.

Placek, charged with conspiracy to commit computer fraud, will surrender once a federal judge in Pittsburgh orders him to appear. His attorney didn't immediately return a call.

Those charged are accused of crimes including conspiring to commit computer fraud, wire fraud and money laundering, selling and using malware programs that could steal data from computers and cellphones and using “bot” networks to take over computers and send spam emails.

Wire services