The union responded to the incident with a statement signed by its general secretary, Mr. Peters Adeyemi. A copy of the statement was sent to the News Agency of Nigeria (NAN) on Sunday in Abuja.
On November 1, Ajaero was attacked in Imo while visiting the state in the Southeast to announce a large-scale demonstration against purported labor violations.
There were reports that he was later taken into custody by the Police, however they have stated that they placed him in their care to protect him from more attacks by thugs.
The assault on the union leader, according to Adeyemi, was "a violation of trade union rights as well as Ajaero's human rights."
"The International Labour Organization (ILO) Conventions and the Federal Republic of Nigeria 1999 Constitution (as amended) guarantee the rights that Ajaero was exercising in Owerri as the leader of the working people of Nigeria."
"The ILO Conventions on Freedom of Association and Protection of Rights to Organise, 1948 (No.87), and the Right to Organise and Collective Bargaining, 1949 (No.98)," he stated, "have been ratified by Nigeria as a member state of the ILO."
Adeyemi, who is also Public Service International's (PSI) deputy president, charged the Imo administration with unfair labor practices.
"Salaries and pensions have not been paid by the government; it is not appropriate to criticize workers' union leaders for inquiring as to why these funds have not been paid," the statement read.
He continued by saying that Ajaero shouldn't have been visited with tendencies "which were common in Nigeria only during military regimes" because he was on a solidarity visit to the workers in Imo.
NASU urged President Bola Tinubu to launch a comprehensive probe into the incident and refuted the assertions that Ajaero was held in "protective custody" for his own benefit.
According to the statement, trade unions would be guaranteed that they wouldn't face a crackdown in the event of a disagreement between the government and labor.