Tokyo police plan to summon a former Russian diplomat once posted in Japan for questioning about restricted information possibly received from a former Ground Self-Defense Force commander suspected of breaching confidentiality laws, an investigative source said.

The ex-envoy is an intelligence officer in the GRU, Russia's military intelligence body, and was posted as a diplomat at the Russian Embassy in Tokyo, the source said Friday.

Since the officer has already repatriated, the summons from the Metropolitan Police Department's Public Security Bureau is likely to end up being a mere gesture.

The source said a 64-year-old former commander of the GSDF's Eastern Army, which oversees Tokyo and 10 prefectures in eastern Japan, is suspected of passing the Russian an SDF booklet describing the operations of its divisions and brigades.

Although the document is available at a shop in the Defense Ministry, the buyer is required to provide name and affiliation, a condition that was imposed after resales of the booklet were deemed problematic.

The Public Security Bureau has searched the home of the former commander in Saitama Prefecture. The bureau is preparing papers on him for prosecutors who may consider a formal indictment against the man for violating confidentiality provisions under the laws governing the SDF, according to the source.

The former GSDF commander has broadly admitted to the allegations, the source said. He is believed to have known the Russian agent for several years, the source added.

The bureau is also planning to send information to prosecutors for the possible indictment of several other people, including an active SDF officer, concerning the violation, because it believes copies of the booklet were acquired by subordinates of the former commander.