Suspicion of nepotism raised in Seoul Metro during the parliamentary inspection of the government is spreading to other public institutions.

Seoul Metro, which operates eight subway lines in the capital, hired 109 relatives of regular staff as indefinite-term contract workers, then turned them into regular staff.

Korea Gas Corp. decided to turn 1,203 irregular workers into regular employees and 25 of them were found to be parents, spouses, siblings and cousins of regular workers.

Daejeon City Corp. hired children, brothers and sisters of its union members as indefinite-term contract workers.

Kepco Plant Service & Engineering recruited 40 children, brothers and sisters of its employees from 2014 to October this year. It turned 240 irregular workers into staff members in April, and 11 of them are children of employees who had joined the company earlier.

Similar cases were found in Hanil General Hospital run by a Kepco-controlled medical foundation, and Korea Land and Geospatial InformaiX.

Probably these are not all.

Now inspections by the parliament and the Board of Audit and Inspection, and also a government survey of all public organizations and prosecutorial investigation are inevitable.

Seoul Metro said 99.8 percent of its employees had responded to its survey on the relatives of employees, but the response rate was found to be a sham.

The company did not collect questionnaires directly from each employee, but received reports from departments.

It regarded the submission of a report by a department as if all of its members responded.

But a son of a senior official who was former union leader and the wife of a personnel affairs manager were found belatedly missing from the list of relatives of employees.

An employee said to a news media anonymously, “no one answered questions sent to them in their group chat room on KakaoTalk.” Another said, “those on leave or business trips were excluded from the survey.”

Eventually Seoul Metro confessed it did not know how many employees responded or whether employees actually answered or whether they lied.

Seoul City, which oversees the subway line operator, tries to avoid responsibility, saying it did not receive proper reports from Seoul Metro.

Nepotism in Seoul Metro shows the epitome of injustice. It infuriates many young job seekers struggling to find jobs. It is a serious problem to tackle with every possible means.

But the government and the ruling Democratic Party of Korea seem to bother to look away, while paying more attention to irregularities recently revealed in kindergartens.

Is it because Seoul City and the Korean Confederation of Trade Unions, to which Seoul Metro union belongs, are sympathetic to the current government?

The ruling party argues suspicions of nepotism are “exaggeration” and “instigation of false information.”

Seoul Mayor Park Won-soon said on his Facebook on Sunday that the opposition Liberty Korea Party is trying to justify discriminating against irregular workers and that the party mentions nepotism to attack President Moon Jae-in’s policy to turn irregular workers into regular staff.

His remarks are misleading.

The fact that Seoul Metro hired 109 relatives of employees as contract workers then turned them into regular staff is not a matter of whether irregulars should face lesser treatment.

It is a case exposing employment unfairness, poor ethical standards and possible corruption.

Park must not try to gloss over the issue as a fight between those who work for irregular workers, like himself, and those who work against them.

Opposition parties on Monday submitted a joint motion calling for a parliamentary investigation into alleged nepotism at public corporations.

The two leftist parties sympathetic with the ruling party -- the Party for Democracy and Peace and the Justice Party -- are in the same boat as the conservative opposition parties this time.

This shows how serious this issue is. Public opinion demands that police and prosecutors investigate even without receiving complaints.

There is no justification to oppose the passage of the motion. A parliamentary inspection should begin quickly.