China on Monday ordered video sites to clean up cartoons recently uploaded online that use iconic cartoon characters in sexual and violent situations.

The National Office Against Pornographic and Illegal Publications said in a statement on Monday that it had launched a nationwide campaign to crack down on the harmful videos.

"We'll keep an eye out for whether those websites carry out self-examination and clean up the videos. Any company that fails to fulfill its corporate responsibility and continues distributing the videos will be severely punished," it said.

Beijing authorities, including the public security bureau and cyberspace administration, also asked search engines on Monday to block related keywords.

Chinese video companies Tencent video, iQIYI and Youku, announced on Saturday that they have started the cleanup campaign and welcomed tips from the public.

The recent action was sparked by the translation of an English article titled "A group of perverts are targeting kids on YouTube. I used to work for them," which was published on social network Reddit in November and went viral on Chinese social media.

The article details the author's experience working in an animation firm that makes cartoon knockoffs of popular children's characters, typically Spiderman, Elsa and SpongeBob into scenes of violence or sexuality to lure children into watching. The videos were shared on You-Tube.

A controversy dubbed Elsagate began in Western countries after Elsa－the main character of the 2013 Disney animated film Frozen－was frequently being depicted in such situations as getting pregnant or undergoing surgery.

YouTube started closing the related accounts and by November declared that it had deleted more than 150,000 videos, foreign media has reported.

Whether true or false, the article aroused Chinese people's concern about the harmful videos－both imported or domestically-made－available on Chinese video portals and video-sharing sites in categories such as children or family with search keywords of the original cartoons.

The capital also launched a campaign against online games that distort Chinese history, discredit heroes, violate the national religious policy, or promote violence or pornography, to develop a healthy network environment for children.