The directive came in a resolution following a motion sponsored by Sen. Mao Ohuabunwa (PDP-Abia).
The NHIS has been embroiled in crisis over allegations of fraud and high-handedness against the Executive Secretary, Prof. Yusuf Usman, by the Governing Council.
It got to a head recently when Usman forced his way into his office after he had been suspended by the council.
The Federal Government intervened by sending the ES on administrative leave, and constituting a panel to investigate the allegations against him.
In the motion, Ohuabunwa listed the allegations against the NHIS boss to include high-handedness, budget distortion, fraudulent cost manipulation, illegal investments and unprofessional manipulation of human resources.
“All these are issues that have pitched the NHIS against its employees and its board, while jeopardising the interests of the general public,” he said.
The senator said the same scenario is playing out in the NPHCDA, where the Executive Director (Dr Faisal Shuaib) is facing similar accusations.
“Many of our public agencies today have moved away from the direct focus on serving the citizens to advance economic and social development.
“Rather, they are now furthering impunity that borders on personality cults, and these certainly run counter to the objectives of the federal government.
“These unguarded executive and administrative processes pervading our public agencies, if not verified, checked and redirected for good, will seriously impair the important roles of our public agencies in advancing the economic, social and general well-being of our citizens.
“As a result, our nascent democracy will gradually lose its steam to emerging impunity of government appointed self-serving titans now looming large,” he said.
Ohuabunwa urged the Senate to exercise its constitutional powers of oversight by intervening and to get to the root of the crises.
President of the Senate, Bukola Saraki, therefore put the motion to a voice vote and it was unanimously adopted by the lawmakers.
The resolution specifically mandated the Senate Joint Committee on Primary Health Care and Communicable Diseases and Health to “thoroughly investigate the matter and other infractions, and inform the Senate of its findings in two weeks.”