The labor ministry has released monthly jobs data despite knowing that it did not satisfy sampling standards and was erroneous, officials said Tuesday.
The revelation could undermine confidence in the accuracy of key economic indicators as Japan enjoys a prolonged phase of economic expansion.
Under existing rules, the ministry has to gather data from all companies with 500 or more employees. But a recent survey covered only a third of the roughly 1,400 businesses in Tokyo that should have been polled.
The monthly labor survey for October was released on Dec. 7. The ministry released its revised version on Dec. 21, but did not reveal that its data-gathering had been inappropriate.
Speaking at a news conference, labor minister Takumi Nemoto said the problem was reported to him on Dec. 20, adding that he has instructed officials to find out why the latest incident took place.
The monthly labor survey serves as a key indicator of the country's employment conditions, covering over 30,000 business establishments across Japan and also including selected firms with fewer than 500 workers.
Employment conditions are closely watched by the government of Prime Minister Shinzo Abe and the Bank of Japan as wage growth is vital for the nation to break with deflation. The job market is tight due to an acute labor shortage, while wage growth has been modest.