Opposition lawmakers have accused the Abe administration of purposely using questionable data to shore up key labor statistics to highlight its economic achievements.

At issue is a Jan. 11 admission by the labor ministry that faulty methods had been used for years to compile the Monthly Labor Survey reports that are used, among other things, to determine unemployment benefits and worker's compensation.

While ministry officials denied there was any organized attempt to fudge the data, no explanation was forthcoming as to why the method kicked off from 2004 nor why a statistical correction was deemed to be necessary from January 2018.

Until the Jan. 11 news conference, labor ministry officials had never publicized the change in the data compilation method or the subsequent correction.

One result of the different method used in calculating wage levels is that about 19.73 million people were shortchanged by about 56.75 billion yen ($524 million) in insurance benefits.

The correction now in place is intended to ensure that the statistics are more in step with the actual monthly wages paid out.

However, opposition parties are focusing on the timing of the correction, asserting that ministry officials may have had an ulterior motive of wanting to bolster Prime Minister Shinzo Abe's goal of being able to announce that his "Abenomics" package of economic measures had led to higher wages.

The basic rule for calculating monthly wages of working people in Tokyo was to cover all companies with 500 or more employees. But from 2004, that rule was bent and only about one-third of such companies were randomly selected to calculate wage rates.

By studying the situation at a smaller number of companies, the average monthly wage turned out to be lower than the actual figure.

The correction from January 2018 led to wage figures that were much closer to reality. In addition, that correction produced higher increase rates in wages over the same month of the previous year.

As a result, the total of monthly wages for June 2018 was found to have increased by 3.3 percent over June 2017, the highest increase rate in 21 years and five months.

Opposition parties are not buying the explanation offered by the government.

Akira Koike of the Japanese Communist Party said, "The responsibility of Prime Minister Abe will have to be questioned since he has repeatedly said that higher wages was one result of Abenomics, while such arguments were being made based on fabricated data."

Akira Nagatsuma of the Constitutional Democratic Party of Japan has called for deliberations even though the Diet is not currently in session on grounds the issue "shakes trust in Japan as a nation."

Labor ministry officials denied any motive to intentionally manipulate the data for political purposes.

Still, ruling party officials quickly realized that immediate action would have to be taken.

Hiroshi Moriyama, chair of the ruling Liberal Democratic Party's Diet Affairs Committee, said on Jan. 11 that he would push for a meeting of directors of the Lower House Health, Labor and Welfare Committee in the coming week in order to decide on the holding of hearings on the ministry data-gathering methods.