Japanese police are considering allowing investigators to go undercover using fake IDs to tackle an upsurge in robberies committed by people recruited online for so-called "shady" part-time jobs.

Informed sources told NHK that the National Police Agency is considering launching undercover investigations in an effort to root out recruiters and those who direct the perpetrators.

Undercover investigators would contact criminal group members by applying for shady part-time jobs.

Potential perpetrators are recruited through social media posts, among other means. Recruiters instruct them to use a highly secure messaging app and send their personal information. Some suspects told investigators that the recruiters used their personal information to threaten them and force them to commit crimes.

Generally speaking, creating a fake ID card is a punishable act. But law-enforcement authorities contend that issuing fake IDs to investigators does not violate current law.

According to the Penal Code, "An act performed in accordance with laws and regulations or in the pursuit of lawful business is not punishable."

Since August, 46 people have been arrested in connection with a series of robbery cases involving shady job applicants, mainly in the Tokyo metropolitan area.

The agency is hoping to launch the undercover investigations as soon as next year after coordinating with relevant government offices and performing necessary procedures, such as drawing up guidelines.