The organization in charge of managing Japan's public pension programs says more than 970,000 pensioners have been sent payout notices with somebody else's personal information.
The Japan Pension Service says the wrong notices were sent out to pensioners in Aichi, Mie and Fukuoka prefectures on Monday and Tuesday.
It apologized and attributed the blunder to errors by a contractor for the printing job. It says the firm printed the data of different pensioners on the address side and the content side of the notice.
The incorrect information included the amount, the basic pension number and the name of the financial institution with the recipient's account.
The Japan Pension Service says the information does not include the pensioner's name or bank account number, so the recipient cannot be identified with it.
Welfare Minister Goto Shigeyuki has apologized for the problem. He pledged to prevent a recurrence by strengthening supervision of the pension service.
Goto said he instructed the organization to make sure there will be no mistakes in the actual transfers scheduled for October 15.
He also told the service to do its best to respond to questions from pensioners, to swiftly find out what went wrong and take steps to prevent a recurrence.
Goto said he reported the issue to Prime Minister Kishida Fumio, who told him the ministry should make thorough efforts to investigate the matter, improve the system and help ease people's concerns.