Mayor Bill de Blasio's administration said Thursday it is canceling approvals that were granted by their predecessors to allow three charter schools to locate in traditional public school buildings.

The move halts the expansion of the Success Academy Charter Schools system. All three scrapped locations are Success schools in the city that were approved under former Mayor Michael Bloomberg.

"While the circumstances for each proposal are unique, we identified clear criteria and we followed it," Schools Chancellor Carmen Fariña said in a statement. "But more importantly, as enrollment deadlines approach, we considered the thousands of families that could be affected. We were deliberate in our decisions and, under the circumstances we inherited, believe this is the best approach."

In another change, American Charter Dream School had requested putting four classes per grade in a Bronx building, but the Department of Education instead wants it to open just three because of space constraints.

De Blasio has long said he wants to place a moratorium on putting charter schools -- taxpayer-funded but privately run institutions -- in traditional public schools. He has said that he believes Department of Education resources should be focused on traditional public schools and that Bloomberg unfairly favored charters. De Blasio wants to charge some charters rent to share public school space.

Success CEO Eva Moskowitz was to address the decision later Thursday.

National Alliance for Public Charter Schools CEO Nina Rees came to Success' defense. At Success Academy's Harlem 4, she said, "83 percent of the students passed the state math exam last year, putting it in the top 1 percent of all schools in the state. Why would anyone want to stop that kind of student achievement?"

United Federation of Teachers President Michael Mulgrew sided with de Blasio and Fariña.

"I'm glad the DOE has taken an important first step in vetoing some particularly troublesome pending co-locations," Mulgrew said in a statement. "But the solution to Bloomberg's destructive policies -- including his two-minutes to-midnight attempt to lock in new co-locations on the new administration -- is to give local schools and communities a real say on how their buildings are used."