A national campaign has been launched against online videos that use iconic cartoon characters in sexual and violent situations, authorities said on Monday.

The campaign recently began in Beijing and Guangdong province and has now become a nationwide effort.

The crackdown will end in late April, authorities added.

"Recently, some livestreaming videos with vulgar content and some online videos in which cartoon characters broadcast violent or sexual content have been spreading online, and these have misled juveniles and harmed their health," they said.

In this situation, the five authorities, including China's Cyberspace Administration and the National Office Against Pornographic and Illegal Publications, decided to conduct the two-month national cleanup.

"Illegal or improper information must be deleted and sites without a livestreaming license will be shut down," they said. "Those broadcasting harmful content and websites having seriously illegal content will be also held criminally liable."

Online platforms providing livestreaming, videos and games, as well as those with many users, are the major targets of the crackdown, "and we will urge them to take responsibility for reviewing the uploaded content", they added.

On Feb 5, for example, police in Tianhe district of Guangzhou filed a case in which a local company allegedly produced and broadcast videos with violent depictions involving cartoon characters online, and the next day the district's industrial and commercial departments revoked its business license, it said.

Some video service providers, including Tencent and Youku, which signed contracts with the company in November 2016, are also being investigated, it added.

"The campaign is to solve new problems brought by livestreaming, as well as to protect our cybersecurity," said Zhu Wei, deputy director of the China University of Political Science and Law's media legal center.

Ensuring the safety of online content is not only to prevent children from being harmed, but also to clarify for online service operators what must not be posted in cyberspace, he said.

"The crackdown should be conducted regularly," he suggested.

In January, some videos were found using popular cartoon characters, such as Elsa from Disney's Frozen and SpongeBob, in scenes of violence or sexuality to lure children to watch.

Since then, Chinese video companies such as Tencent video and Youku, have announced the start of the cleanup and welcomed tips from the public.