The city has announced that some pre-kindergarten centers won't be opening this school year.

With just hours to go before school starts, Mayor Bill de Blasio closed nine city pre-K centers, two of them in Brooklyn, due to health and safety concerns.

The first day of school will also be delayed for 36 other centers. Those affected students will have to make up the missed days at a later time.

De Blasio says there is a plan for the displaced children enrolled in those facilities, and that every child that is signed up for full-day pre-K will still be guaranteed a spot.

The Birch Family Services Center in East Flatbush and the Child Development Support Corporation in Clinton Hill were told by city officials that they would not open this year because they didn't pass inspection.

The city is working to find alternative locations for the displaced students, but City Comptroller Scott Stringer, who reviewed some of the pre-K contracts, says the mayor is downplaying the safety concerns.

Stringer says that there are still missing hundreds of contracts from facilities.

De Blasio said the central focus is to make sure the sites are safe before students arrive.

Education officials are stressing that the vast majority of centers will open on schedule Thursday, allowing more than 50,000 students to attend the city's expanded universal pre-K program.