Us and Korean authorities have said they have broken up in one of the world’s largest child pornography markets, a crime that is spreading at a furious pace with the rise of cryptocurrency and encrypted online content.

The bust was revealed Wednesday when the U.S. unsealed an indictment against 23-year-old Chung Woo Song, who prosecutors say ran a darknet market that accepted bitcoin and distributed more than 1 million videos of a sexual nature involving children. Son, a South Korean citizen, is serving 18 months in prison after being convicted there.

Since agents shut down the site in March 2018, authorities have arrested 337 users of the sites worldwide. According to us authorities, they were in countries such as the UK, Germany, Brazil, Saudi Arabia and the United Arab Emirates, as well as nearly two dozen US States. The UK government said people in 38 countries had been arrested.

“What we are here to discuss today, the sexual exploitation of children, is one of the worst forms of human evil imaginable,” Jesse Liu, the U.S. attorney for the district of Columbia, said Wednesday as she announced the charges.

Images of sexual exploitation have grown since 2014, when the national center for missing and exploited children received reports of 1.1 million cases of child pornography. By last year, that number had risen to 18.4 million.

Son’s website called Welcome to Video contained over 250,000 unique videos. Of those, 45% contained new images that were previously unknown, according to the National center for missing and exploited children.

The site operated as a “hidden service” on the Tor network that hid the location of the operator and users, Deputy assistant attorney General Richard Downing said.

Child sex offenders have created online communities that “brazenly encourage the victimization of children and even infants, educate members on how to commit abuse, avoid getting caught, encourage members to document their abuse, and distribute these videos and photos to predator groups,” Downing said.

Investigators from the IRS and Homeland security Investigations have worked with law enforcement agencies around the world, including the national crime Agency NCA. The Agency said it discovered the Welcome to Video site while investigating the man, who is currently serving a 25-year prison sentence, and that it identified the Son as the cameraman.

Neil Weinberg of Bloomberg News contributed to this article.

Section from 10/17/2019