The Coalition of United Political Parties (CUPP), a group of opposition political parties, has threatened a mass protest on January 15 if the Inspector-General of Police, Ibrahim Idris, is not retired.
According to civil service statutes, the occupant of the office of the Inspector General of Police is to resign after spending the mandatory 35 years in service or attaining 60 years of age.
Mr Idris is expected to retire from service after reaching the mandatory 35 years in service this month.
Last week, President Muhammadu Buhari held a closed-door meeting with Mr Idris amid speculations that his tenure as the police boss would be extended.
In a statement on Sunday, CUPP said it would hold nationwide protests to force the government to back down on any plans to extend Mr Idris' stay in office.
"It is flowing from this and to save our dear country from further drift from a government that lacks capacity to provide leadership to our country, that the secretariat of CUPP hereby directs all coalition members in the 36 states to begin preparation for nationwide protests from January 15, if the retired IG is seen dressed in police uniform around the Force Headquarters," said Imo Ugochinyere, CUPP's national spokesperson.
The protests, according to the statement, would hold in front of the police command headquarters of every state and would continue till "the right thing is done."
Mr Ugochinyere said the protests would begin if Mr Idris is seen in police uniform around the force headquarters from January 15.
He added that with Mr Idris' tenure having come to an end on January 3, the Inspector General of Police office is now vacant.
"The IG is constitutionally barred from being retained or reappointed as the IG as he is no longer a serving police officer.
"His continued stay in office is illegal and an act of impersonation as there is no legal or documentary evidence to back up his stay as the IG."
Making reference to Section 215(1)a of the 1999 Constitution, which he said, held that the president could only appoint a serving police officer, CUPP called on the president to announce a replacement or he would be held responsible if there is a breakdown of law and order.
"We call on President Buhari to be courageous to announce the replacement and not bow to the pressure to cement illegality in the core of the nation's security architecture due to his desperation to rig himself back to power, knowing he has been rejected by the Nigerian people."