Image copyright AP Image caption Ms Dolezal has said she considers herself black

Rachel Dolezal, the US race activist accused of "pretending to be black", once sued her university for racism, according to US media reports.

However, she sued the historically black Howard University, for favouring African American students over herself as a white student.

On Monday, Ms Dolezal resigned from the anti-racism organisation NAACP, after her parents said she was in fact white.

She has previously claimed to be the victim of hate crimes for being black.

Black university

Ms Dolezal, then known as Rachel Moore, received a Master of Fine Arts degree from Howard University in 2002.

Court documents obtained by the Smoking Gun website show that she sued the university that same year for "discrimination based on race, pregnancy, family responsibilities and gender".

As part of her claim, she alleged that some of her artwork had been removed from an exhibition in order to favour black students.

She said the art was removed from the 2001 exhibition because Howard University was "motivated by a discriminatory purpose to favour African-American students over".

Image copyright AP Image caption Rachel Dolezal sings the civil rights anthem "We Shall Overcome" at a rally in March 2015

The case was dismissed in 2004, with no evidence found that Ms Dolezal had been discriminated against. That decision was upheld by the Court of Appeal in 2005. She was ordered to pay costs of $2,728.50 (£1,752) to Howard.

It is estimated that 93% of Howard University students are black, while only 1% are white. Its alumni include the writer Nobel Prize winning novelist Toni Morrison.

NAACP resignation

Ms Dolezal's estranged parents say her origins are mostly white, with a small amount of Native American ancestry. They say that she has no black origins.

Her mother, Rutheanne Dolezal, told the Victoria Derbyshire programme on Tuesday that her daughter had become "disconnected from reality."

She has produced childhood pictures of her daughter with pale skin, freckles and fair hair.

On Monday, Rachel Dolezal resigned as president of the The National Association for the Advancement of Colored People's Spokane Chapter in Washington in the wake of the race row.

"In the eye of this current storm, I can see that a separation of family and organizational outcomes is in the best interest of the NAACP. Please know I will never stop fighting for human rights," she wrote on the group's Facebook page.

An online petition calling for her to step down received hundred of signatures.

She had already lost her job as a lecturer in African-American studies at a local university.

In an interview Ms Dolezal said that she would like to be described as black. "I prefer black, and I would say that if I was asked I would say that... I do consider myself to be black."

According to the Spokesman-Review newspaper, Ms Dolezal said she was a mix of white, black and American Indian on her application to serve on Spokane's citizen police ombudsman commission in January.

The city's ethics committee said it was investigating the allegations, in addition to a separate investigation related to Ms Dolezal on a different matter.