The National Police Agency said Thursday that an Internet watchdog acting on its behalf has been looking out for online blueprints for 3-D printed guns and requesting that Internet service providers remove them whenever they are found.

While it is not illegal to publish gun designs on the Internet, the agency has asked the Internet Hotline Center to take action following the arrest of a man by Kanagawa Prefectural Police in May on a charge of possessing a gun manufactured by a 3-D printer produced using data acquired online.

The IHC has been implementing this and other monitoring actions since Friday after the police agency demanded changes in its guidelines for requesting removal of online material, agency sources said.

The new purge list includes information promoting voyeurism and stalking and on how to obtain copies of resident registration cards illegally.

Since July, a voluntary watchdog set up by Net businesses called the Safer Internet Association has been requesting providers delete websites carrying images that suggest child bullying or revenge porn as well as web pages promoting dangerous drugs.

Both organizations will alert the police about any sites they blacklist.