Tokyo police on Tuesday arrested a self-styled doctor who is suspected of practicing medicine without a license for eight years at about 20 medical institutions.

Hideki Yamashiro, 33, a resident of Meguro Ward, was arrested for allegedly diagnosing and prescribing drugs to a 49-year-old patient at a surgical hospital in Tokyo's Edogawa Ward in mid-September without a medical license, the police said.

Police said Yamashiro is currently a doctor on staff at three privately run hospitals in Tokyo and earns about 20 million yen annually.

Yamashiro has admitted to the allegations, which are violations of the Medical Practitioners Law, they said.

The police believe he used a forged medical license to get hired at the hospitals and used the identification number of an actual doctor.

Yamashiro is thought to have begun his medical career in 1997 at Tokyo Metropolitan Hiroo General Hospital, police said.

However, the hospital said that while its records show a Hideki Yamashiro was listed as an observing student, the person never participated in any medical procedures and was never under its employ.

The man has never attended medical school and dropped out of a night course to finish high school, police sources said.

Sassa General Hospital in the city of Nishitokyo, western Tokyo, is one of the three hospitals that currently employ Yamashiro.

Sassa General said Yamashiro has been working about once a week since August 2003 but that he was hired through a medical recruitment agency and therefore could not have his credentials verified.

Sassa General said it has never received any complaints about Yamashiro from patients.