Prime Minister Shinzo Abe says he will strengthen the independence of a panel that is investigating the flawed statistics compiled by the labor ministry.
Abe was responding to questions by Tetsuro Fukuyama, the Secretary General of the Constitutional Democratic Party of Japan, in an Upper House session on Friday.
Japan's governing party lawmakers have criticized labor ministry officials for their poor grasp of the facts surrounding a fresh discovery of faulty statistics.
The labor ministry admitted earlier this week that improper methods were used for its wage structure survey. Questionnaires were sent to businesses by post, although officials were supposed to hand-deliver them.
Japan's labor ministry said on Monday that flaws have been found in statistics used to determine the minimum wage. It is the second time problems relating to the ministry's statistics have come to light in the past month.
The labor ministry admitted that its basic survey on wage structure was conducted with improper methods. The survey aims to obtain a clear picture of how wages are paid, according to employment type or occupation.
Japanese lawmakers from both the ruling and opposition parties have heaped criticism on the labor ministry for conducting faulty labor surveys for years.
The Lower House health and labor committee deliberated on the issue on Thursday, despite the Diet being out of session. The discussions followed the release of a report on the defective surveys by an investigation panel.
A committee investigating the faulty statistics survey of Japan's labor ministry is focused on whether there was systematic involvement in misconduct or cover-ups.
The labor ministry was supposed to cover all large businesses in Tokyo for its monthly statistics report on wages and hours, but was found to have been surveying only a fraction of them.
An independent panel has found that Japan's labor ministry threw away statistical data that should be kept permanently, in the latest development in a scandal involving faulty surveys of wages and working hours.
The panel on Tuesday presented its report on the ministry's use of improper methods for its monthly surveys.
Japan's labor ministry has launched an external investigation panel to look into the use of an improper method for collecting job data.
The ministry is supposed to survey all businesses with payrolls of at least 500 people to compile its monthly labor surveys. But it was recently revealed that the ministry only covered a third of such firms in Tokyo for years, resulting in incorrect data for wages and work hours.
Japan's top government spokesman has harshly criticized South Korean President Moon Jae-in for his remarks about South Korean court rulings on wartime labor.
Moon referred on Thursday to the ruling that ordered Nippon Steel & Sumitomo Metal to compensate South Korean plaintiffs who say they were forced to work for the Japanese company during World War Two.
Japan's labor minister has pledged to find out why his ministry kept releasing improper job statistics that apparently led to underpayment of benefits to millions of people.
At a news conference on Friday, Takumi Nemoto offered deep apologies for causing trouble to the public over the ministry's release of statistics compiled through improper methods for years. The data in question cover corporate salaries and working hours surveyed monthly.