The principal of one of New York City’s top public schools, Brooklyn Technical High School, beefed up supervision of boys’ bathrooms this week after finding racist and anti-Semitic imagery inside them, emails show.

Principal David Newman also alerted students just before Martin Luther King Jr. Day this month that an adult working in the building received a “deplorable email” using a racist derogatory term, and he will suspend students who use hate speech, according to an email to parents. Further, the principal said he would alert all colleges that perpetrators apply to about suspensions for certain infractions.

“This community will stand together against intolerance, hatred and harmful speech!” his email said.

City Department of Education officials said Thursday it isn’t the agency’s policy to report such incidents to colleges, but they were referred to the Special Commissioner of Investigation.

“There’s absolutely no place for bigotry in our schools, and these issues are being thoroughly investigated,” said department spokeswoman Miranda Barbot. “We’re providing additional counseling to students, and anti-bias training for all Brooklyn Tech staff.”