Tennis legend Martina Navratilova has apologized for calling transgender athletes “cheats.”

Last month, Navratilova, who came out lesbian in 1981, wrote an op-ed published in the Sunday Times of London titled “The Rules on Trans Athletes Rewards Cheats and Punish the Innocent.”

“It's insane and it's cheating,” she wrote.

“Simply reducing hormone levels – the prescription most sports have adopted – does not solve the problem. A man builds up muscle and bone density, as well as a greater number of oxygen-carrying red blood cells, from childhood,” Navratilova said, a reference to guidelines that specify testosterone levels for transgender women to compete.

Writing on her personal website over the weekend, Navratilova said that she was sorry for using the word “cheat.”

“I know that my use of the word 'cheat' caused particular offense among the transgender community,” she wrote. “I'm sorry for that because I certainly was not suggesting that transgender athletes in general are cheats.”

Navratilova suggested that she was unfairly criticized.

“The support I normally get from 'my people,' the LGBT community, was replaced by a barrage of quite nasty personal attacks,” she wrote.

She added that her concern was for a level playing field.

“All I am trying to do is to make sure girls and women who were born female are competing on as level a playing field as possible within their sport,” Navratilova said.

Athlete Ally, a non-profit dedicated to ending homophobia and transphobia in sports, responded to Navratilova's original comments by dropping her from its advisory board and removing her from its ambassador program.

The group called Navratilova's comments “transphobic” and accused her of promoting “dangerous myths that lead to the ongoing targeting of trans people through discriminatory laws, hateful stereotypes and disproportionate violence.”