The operation, dubbed Operation SpecTor, involved multiple law enforcement agencies and was conducted across the United States, Europe, and South America.

U.S. Attorney General Merrick Garland said the sweep led to the seizure of 117 firearms, 850 kilograms of drugs and $53.4 million in cash and virtual currencies.

Of the 288 arrests, he said 153 defendants were arrested on U.S. soil.

"Our message to criminals on the dark web is this: You can try to hide in the furthest reaches of the internet, but the Justice Department will find you and hold you accountable for your crimes," Garland said at a press conference.

(Reporting by Sarah N. Lynch and Jasper Ward; Editing by Doina Chiacu and Christina Fincher)

By Sarah N. Lynch and Jasper Ward