A male student accused of raping his classmate has sued Columbia University for failing to protect him against backlash and harassment.

Authorities rejected Emma Sulkowicz's case that Paul Nungesser, a German citizen, was a 'serial rapist' who assaulted her after class.

Nonetheless, the case gathered international attention as Sulkowicz, a senior majoring in visual arts, publicly paraded her mattress in protest, calling for his indictment.

And according to Nungesser's lawsuit citing 'gender-based harassment and defamation', Columbia presented the allegations as fact on a university-owned website.

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'No protection': Paul Nungesser is suing Columbia University for allowing Emma Sulkowicz to parade the school and take campus-provided transport with her mattress in protest against him, calling him a rapist

The lawsuit was filed in Manhattan federal court on Thursday, three days after a judge tossed out another gender-based lawsuit brought by a male student against Columbia University.

Defendants include the school, its board of trustees, President Lee C. Bollinger and Professor Jon Kessler. The lawsuit sought unspecified damages.

'Columbia University's effective sponsorship of the gender-based harassment and defamation of Paul resulted in an intimidating, hostile, demeaning ... learning and living environment,' the lawsuit said.

Roger Hornsby, a Columbia spokesman, said the school had no comment. Email messages requesting comment from Bollinger and Kessler were not immediately returned.

In his lawsuit, Nungesser said a Columbia-owned website had presented as fact that he sexually assaulted Sulkowicz, a senior majoring in visual arts.

It said that the school allowed Sulkowicz to carry a mattress into classes, the library and campus-provided transportation as part of her senior thesis, that Kessler approved the 'Mattress Project' for her course credit and that Sulkowicz's pledge to carry her mattress to graduation may prevent Nungesser and his parents, who'd like to fly from Germany, from participating in graduation ceremonies.

'Day-to-day life is unbearably stressful, as Emma and her mattress parade around campus each and every day,' the suit said.

As a result of publicity that resulted in media reports in 35 countries, the lawsuit said, Nungesser 'has been subjected to severe, pervasive ... and threatening behavior by other Columbia students, believing that Paul is a `serial rapist,' whenever Paul has appeared at university activities.'

Nungesser became the target of international attacks following the claims, which were dismissed by a judge

The complaint also said he wants to stay in the United States, where he has been dating a girlfriend for over a year, and is seeking consulting work in New York, though job prospects have been 'severely jeopardized' by the school's support of Sulkowicz.

In an email responding to a request for comment, Sulkowicz wrote: 'I think it's ridiculous that Paul would sue not only the school but one of my past professors for allowing me to make an art piece.

'It's ridiculous that he would read it as a `bullying strategy,' especially given his continued public attempts to smear my reputation, when really it's just an artistic expression of the personal trauma I've experienced at Columbia. If artists are not allowed to make art that reflect on our experiences, then how are we to heal?'

Sulkowicz has argued her case was badly mishandled by the school disciplinary panel after she reported in 2013 she was raped in her dorm months before.