WASHINGTON - US authorities working with law enforcement partners 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.

US 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.

Among those charged was Johan Anders Gudmunds of Sollebrunn, Sweden, known as Synthet!c, who the Justice Department said was Darkode’s administrator. Residents of Pennsylvania, New York, Florida, Indiana, Wisconsin, Louisiana, Slovenia, Spain and Pakistan also were indicted.

The Justice Department said the FBI and US 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 and included Israel, Nigeria and Australia. The department said it was the largest coordinated international law enforcement effort ever directed at an online cybercriminal forum, the 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 site hidden by well protected Web servers.

The darkode.com website on Wednesday showed logos of various law enforcement agencies from around the world and a notice saying the domain had been seized by the FBI as part of an investigation with the 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 www.krebsonsecurity.com and had infiltrated the forum 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.”

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 email.