Mayor Bill de Blasio is facing heat for suggesting Wednesday that some sexual harassment complaints at the Department of Education are false.

His comments came as data released Friday night showed that 471 complaints were made in the city education department over the last three years. Only seven of those claims were substantiated. About half of the complaints were withdrawn.

The mayor's office said the substantiation rate was suspiciously low, and that the city would hire 11 more investigators to look into the sexual harassment claims within the city education department. The city currently has seven investigators.

But speaking at an unrelated press conference Wednesday, de Blasio suggested some of the claims may have been fabricated.

"It is a known fact that, unfortunately, there's been bit of a hyper-complaint dynamic, sometimes for the wrong reasons. So I think that has inflated the numbers," de Blasio said. "We need to address that cultural reality within the DOE [Department of Education]."

Reporters pushed de Blasio to clarify his remarks at the press conference, asking if he was saying teachers were lying when they say they have been sexually harassed. Studies have shown that very few complaints of sexual harassment are fabricated.

A few hours after the mayor made the claim, he walked back on his comments:

The head of the teachers union fired back at de Blasio. In a statement, Michael Mulgrew said, "Our teachers have a tough enough job that they don’t have time to make frivolous claims."

The mayor said all city agencies need to be aligned on the issue, and he added that all city employees will be retrained on how to handle sexual harassment.