Amid a spike in copyright infringement, the government on Friday compiled a report calling for an “emergency measure” that would block access to websites that pirate anime and manga.

The Cabinet Office’s Intellectual Property Strategy Headquarters plans to encourage internet service providers to restrict access to such “malicious” websites “on a voluntary basis” in order to protect the nation’s famed manga and anime industries from free-riders.

The report named three major piracy websites — Mangamura, Anitube and Miomio — as targets of the blocking measure.

Online, speculation has been rife that Mangamura, one of the most notorious manga piracy websites, has been shut down, as it has been inaccessible since around Tuesday. The site had over 174 million visitors in March, making it the 25th busiest website in Japan, according to the analysis tool SimilarWeb.

Piracy websites have presented a major headache for manga creators as royalties aren’t paid for content that’s distributed without the consent of the copyright holders.

RELATED STORIES Internet piracy taking major bite out of Japan's famed manga culture

The increasing prevalence of comic book piracy prompted some manga creators’ groups to publish statements warning of the issue. Tokyo-based Manga Japan claimed that the manga industry may “eventually perish” if the situation continues.

But blocking individual sites may not be a stable solution, as a Mangamura copycat has already been launched.

The government regards the move as a temporary measure until it establishes a law to crack down on piracy, including banning so-called leech sites, which aggregate links to illegal copies of manga, music, videos and other files uploaded to other websites.

Current copyright law bans the uploading of illegal copies, but leech sites often claim they aren’t violating the law because they neither upload the files themselves nor have illegal copies on their own computer servers.

The government will also seek to develop a legal basis in 2019 to restrict access to piracy websites.

Critics have expressed concern that blocking certain websites violates Article 21 of the Constitution, which states: “No censorship shall be maintained, nor shall the secrecy of any means of communication be violated.”

The Internet Content Safety Association, an industry organization consisting of internet service providers and IT companies, said Wednesday that piracy websites should be regulated by law rather than by blocking tactics, which the group fears could be used for the censorship of information such as anti-government protests.

Between September and February, the three major piracy websites mentioned by the government have attracted over 938 million visitors combined and may have caused damage totaling more than ¥400 billion to the manga and anime sectors, according to the Content Overseas Distribution Association.

Internet service providers have already blocked their customers from accessing child pornography websites, a decision that was made in 2011.

Related story: Internet piracy taking major bite out of Japan’s famed manga culture