A US university has launched an investigation after a professor admitted she had lied for years about being black and is in fact white -- a stunning admission amid a tense national reckoning on race issues including cultural appropriation.

In a post on the platform Medium, Jessica Krug -- a history professor at George Washington University in the US capital focusing on Africa -- said she had been pretending "for the better part" of her adult life.

"I have eschewed my lived experience as a white Jewish child in suburban Kansas City under various assumed identities within a Blackness that I had no right to claim," she wrote.

Krug, who is light-skinned, said she first claimed "North African Blackness, then US rooted Blackness, then Caribbean rooted Bronx Blackness."

One of her former students told CNN that Krug voiced pride in her Bronx roots, but told another student she was from Puerto Rico.

Krug said on Medium that her actions were the "very epitome of violence, of thievery and appropriation, of the myriad ways in which non-Black people continue to use and abuse Black identities and cultures."

The professor called herself a cultural "leech."

In a statement Friday evening the university said: "While the university reviews this situation, Dr. Krug will not be teaching her classes this semester." It did not say what will happen now with her.

"We want to acknowledge the pain this situation has caused for many in our community," it added.

Krug's situation brought to mind the case of controversial US activist Rachel Dolezal, who made headlines in 2015 after saying she identified as black, even though both of her parents are white.

"I'm more black than I am white," Dolezal said at the time.

Cultural appropriation has become more and more taboo in the United States, notably in progressive and university communities.

Pop diva Adele recently found herself in hot water after posting a photo of herself on Instagram with her hair in Bantu knots, a traditional African hairstyle.