"The committee should state measures, if any, by the Nairobi County Government to regularise the employment of the staffers in case they were irregularly hired as has been alleged in some quarters," the Senate deputy minority whip said.
The ODM secretary-general wants the Senate told whether Nairobi Governor Johnson Sakaja's government would hire replacements for the workers, who he said: "had been released unceremoniously from service."
According to the County Service Board, contracts for the 700 ended with the expiry of the NMS contract last November, with the board ruling out paying them further.
Sakaja is among those expected before the West Pokot Senator Julius Murgor-led committee as it embarks on its investigations.
In February, the county boss ordered that the NMS workers, who had been laid off by the county service board, be absorbed and redeployed within the county government as permanent staff.
The workers would be requested to continue working pending renewal of their contracts, a move that ran afoul with Members of the County Assembly (MCAs).
The Assembly's Justice and Legal Affairs committee directed the sacking of the 700, hired by the NMS in 2021, saying they were in office illegally.
The County Assembly has consistently argued that the staffers were hired irregularly by the Public Service Commission (PSC), given that security and compliance had not been transferred to the NMS.
Last week, the MCAs adopted a report from the Assembly's labour committee that rejected to absorb the sacked officers.
"The cadets were recruited by the PSC whereas the county establishment does not have such cadres," the report read in part.
The labour committee found that the County Service Board had not been involved in recruiting the workers.
The NMS was formed in 2020 after former Governor Mike Sonko signed off key functions to the National Government.