Mayor de Blasio has blocked the city’s investigations chief from taking control of an office that monitors corruption in the public school system.

In his latest slap against independent-minded Department of Investigation Commissioner Mark Peters, de Blasio on Sunday quietly signed an executive order mandating that mayors must approve all removals or appointments of the special commissioner of investigation for the city’s school district.

De Blasio took action mere days after Peters fired Anastasia Coleman — a former prosecutor Peters tapped to run the school district’s Office of the Special Commissioner of Investigation in February — as part of a restructuring plan. The post falls under DOI but had long operated with a great deal of autonomy.

“I was very concerned,” said de Blasio on NY1 cable TV Monday night while explaining his decision. “This is a position that always had its independence, and when I saw [Coleman was fired] I thought it was important to act.”

Both Peters and the mayor were once good friends but have been at odds the past two years over a series of scathing reports DOI has issued against various city agencies, including the Housing Authority.

DOI in a statement said de Blasio’s executive order “limits” the agency’s “appointment authority and challenges its independence over investigations into corruption in city schools. We will continue to root out corruption, waste, fraud and abuse in the school system despite this order.”