Law enforcement officials said on Wednesday they had arrested hundreds of people worldwide after knocking out a South Korea-based dark web child pornography site that sold gruesome videos for digital cash.

Officials from the United States, Britain and South Korea described the network as one of the largest child pornography operations they had encountered to date.

The website, named Welcome To Video, the website relied on the bitcoin cryptocurrency to sell access to 250,000 videos depicting child sexual abuse, authorities said.

"Darknet sites that profit from the sexual exploitation of children are among the most vile and reprehensible forms of criminal behavior," U.S. Assistant Attorney General Brian A. Benczkowski said.

Officials have rescued at least 23 underage victims in the United States, Britain and Spain. Many children in the videos have not yet been identified.

Welcome To Video's operator, a South Korean named Jong Woo Son, and 337 users in 12 different countries, have been charged so far, authorities said.

Son, currently serving an 18-month sentence in South Korea, was also indicted on federal charges in Washington.

Several other people charged in the case have already been convicted and are serving prison sentences of up to 15 years, according to the U.S. Justice Department.

The site is one of the first websites to monetize child pornography using bitcoin, which allows users to hide their identities during financial transactions.

Users were able to redeem the digital currency in return for "points" that they could spend downloading videos or buying all-you-can watch "VIP" accounts. Points could also be earned by uploading fresh child pornography.

"These are the bottom feeders of the criminal world," said Don Fort, chief of criminal investigation at the U.S. Internal Revenue Service (IRS), which initiated the investigation.