M Nageswara Rao first took charge as interim chief of the CBI in October.
M Nageswara Rao's appointment as the interim chief of the Central Bureau of Investigation after the removal of Alok Verma from the top job was challenged in the Supreme Court on Monday.
An NGO filed a petition through advocate Prashant Bhushan seeking a direction to cancel the government's order appointing Mr Rao as the acting director of the agency.
Mr Rao took over the top job last Friday after Mr Verma's sacking by a high-powered panel headed by Prime Minister Narendra Modi. He promptly reversed all decisions taken in the previous two days by his then boss.
Every decision made by Mr Verma was cancelled, sources said. Mr Verma, after returning to work, had reversed many transfers ordered by Mr Rao, mostly of members in his team, and also ordered the transfer of five officers.
The 1986-batch Odisha cadre Indian Police Service officer first took charge as interim chief under dramatic circumstances on October 23, around 2 am, after Mr Verma was divested of his powers and sent away.
The NGO also sought a direction to the government to appoint a regular director of the CBI as per the rules.
(With inputs from PTI)