Law enforcement agencies across the globe staged a crackdown on so-called darknet web sites last week, targeting marchants and thousands of customers who were looking to obtain illegal drugs and goods.

From Oct. 22 to Oct. 28, the agencies took action against merchants and customers that used these sites for illicit items, U.S. Immigration and Customs Enforcement said in a statement on Monday.

Unlike other websites, these underground marketplaces reside within the darknet -- a sort of parallel internet accessible to visitors via anonymizing software like Tor. While the software has legitimate uses, such as safeguarding communications in authoritarian countries, it has been adopted for more illicit means.

Last week's crackdown was global in scale. In addition to the U.S., Europol and law enforcement agencies from Australia, Canada, New Zealand and the U.K. participated in the operation.

In the U.S., the FBI said it made "contact" with 150 individuals suspected of buying illicit items from darknet marketplaces. "Some of these individuals confessed to ordering a range of illegal drugs and controlled substances online, including heroin, cocaine, morphine, and ketamine," the FBI said.

It's unclear how U.S. investigators found out about the suspects' activities. But a video posted online shows agents searching for illegal goods by opening packages at a Los Angeles mail facility. Among the items seized were live turtles sent from Las Vegas, a counterfeit bong made in China, and fake Ray-Ban sunglasses.

In other countries such as Sweden, local police said they had identified more than 3,000 suspected buyers of drugs sold over the darknet. Police were able to identify the suspects because six of the largest Swedish merchants on the darknet had been arrested in the past year.

Police in Netherlands also said they took "some criminal justice actions" as part of last week's operation. Authorities there have even published a website, naming which vendors are still active on the darknet, and which have already been arrested.

Some of those merchants go by usernames that appear on AlphaBay Market, a major underground website known to sell drugs, stolen credit cards and counterfeit items. AlphaBay continues to operate as of Tuesday.

New Zealand police have also said they contacted over 160 people in the country suspected of buying drugs from the websites. The crackdown has so far resulted in six arrests and 66 formal warnings.