A labor union representing teachers at scandal-hit Nova Corp. submitted a petition Tuesday to the Osaka labor standards authority asking it to seek an indictment against the language school chain and President Nozomu Sahashi for breaching labor laws.

The General Union asked the Osaka Central Labor Standards Supervision Office — an arm of the Health, Labor and Welfare Ministry — to have prosecutors indict both Nova and Sahashi for delaying the payment of salaries to foreign teachers.

A separate labor union formed by Nova teachers in the Tokyo metropolitan area filed a similar petition with the Shinjuku Labor Standards Supervision Office.

According to the General Union, wages for the school's 4,000 or so foreign instructors are usually paid in the middle of the month. But the September payments were delayed, and the company has told instructors that the payments for October will be delayed until Friday.

Nova has also failed to pay wages on time to about 2,000 Japanese employees over the past three months.

In late September, the union filed a request with labor authorities asking that Osaka-based Nova be ordered to pay the wages. The authorities have since recommended on a number of occasions that the company improve its labor standards practices.

Article 24 of the Labor Standards Law stipulates that companies must pay wages to employees at least once a month, on a fixed date.

Nova has been suffering from falling student enrollment and increasing contract cancellations after being ordered in June to partially suspend business for deceiving consumers in advertisements about its services.

The order, which crippled its ability to sign up long-term students, is making it increasingly difficult for Nova to pay wages and has prompted reports that it is closing several schools.