Unleashing anger from Upper East Side parents, Department of Education officials last night backed off a plan to move a high school there to East Harlem in order to make space for an elementary school.

Neighborhood parents had praised the plan because it would create a new elementary school with its own space immediately in a baby-boom neighborhood, but teachers and parents at the high school that would have to move called it racist, saying their students — who are mainly black and Hispanic — should not be pushed to a building across from a housing project in order to make room for white families.

The department’s new proposal is to keep the high school where it is and open a new elementary school in temporary quarters, while looking for a permanent space.

The plan would add a new elementary school to a section of the Upper East Side that has not had a local, zoned school for nearly a decade. The unusual situation arose when officials deemed PS 151 unsafe and closed it in 2000. Neighborhood parents and elected officials have been pushing the city to open a replacement for 151, but until recently school officials hedged, saying that nearby schools could accommodate the neighborhood’s children.

Now, population growth in the area has made those schools overcrowded, with anywhere from 8 to 50 percent more students than they are meant to hold.

School officials say the elementary school would only be in temporary space for a short time, because they are examining a permanent location that is smack in the middle of the neighborhood. Architects were on the scene yesterday assessing the “excellent, excellent prospect,” John White, the DOE official in charge of school siting, told parents at a community board meeting last night.

But the new building won’t be ready for at least two years, White said, and so he laid out several options for what to do until then. Under one, PS 151 students would continue to enroll at nearby schools via lotteries until the new building is ready. Under another, they could use the lottery this year, but then start at a new school in 2010, using temporary space that East Side Middle School is about to vacate. The final option would allow them to start the new school immediately, beginning at classrooms inside Wagner Middle School, and then moving to the East Side Middle School location in 2010.

Parents at the community board meeting last night criticized all of the options, saying that their children would be forced to attend schools far from their homes or made to move school buildings as many as three times in three years.

“It’s a traumatic thing to put your 5-year-old on a school bus,” said one mother. She said her son was at the bus stop last year when he witnessed a crane collapse that killed one person.

“The thought that my child would go to one school for one year, another school for one year, then finally go to school in a permanent home — I would run fleeing in the opposite direction so fast,” said Elizabeth Rose, a PTA member at PS 183, which accepts many of the children from the PS 151 zone.

Several parents aimed their criticism squarely at White, saying that he was reversing a promise made in December to open a school for their children this year.

They asked why he was backing off from the proposal he made in December to move the Richard R. Green High School for Teaching, currently located in an old elementary school building on East 88th Street, to East Harlem this fall. Its current building would then be used for a new elementary school to serve the PS 151 zone.

Some Richard R. Green families and staff called that plan racist because most Richard R. Green students are black and Hispanic, and most people living in the neighborhood — the ones whose children would attend the new elementary school — are white. The Green families also objected to the new space they would be forced to transfer into, a shared building across the street from housing projects. “I’ve been around projects my whole life. I don’t want to go to school by one,” a Richard R. Green 10th grader told the Daily News at the time.

Jessica Lappin, a City Council member from the Upper East Side, said she was frustrated by the reversal. “We thought we had a solution,” she said. “We thought we had a plan in place for this fall.”

But White said the department determined that the plan would merely displace overcrowding into high schools, where Manhattan already lacks sufficient seats to accommodate its neediest students.

“We would be creating a problem for the system that would mimic the problems on the Upper East Side, just with a different set of children,” White said.