Media playback is unsupported on your device Media caption Summer Zervos said she had no option but to sue Mr Trump to restore her reputation

A former Apprentice contestant who accuses US President-elect Donald Trump of sexual assault has filed a defamation lawsuit against him.

Summer Zervos, who alleges Mr Trump forced himself on her in 2007, said he lied to the nation about his behaviour.

The lawsuit, which Ms Zervos announced at a news conference, alleges Mr Trump is a "liar and misogynist" who "debased and denigrated" her.

The news came just three days before Mr Trump is sworn in as president.

Mr Trump faced a spate of sexual misconduct allegations in the run up to the election, all of which he has denied.

At the time, he dismissed them as "false and ridiculous" and said they were "sick" and driven by fame, money or politics.

"Since Mr Trump has not issued a retraction, as I requested, he has therefore left me with no alternative but to sue him in order to vindicate my reputation," Ms Zervos told journalists in Los Angeles on Tuesday.

She was joined by her lawyer, Gloria Allred, a Democratic party activist, who said the plaintiff's allegations had passed a lie detector test.

'Thrown under the bus'

Ms Zervos is one of several women who came forward to accuse the incoming 45th president of sexual assault after the October release of a 2005 videotape in which he is heard making lewd comments about groping women.

The 41-year-old former reality show contestant said Mr Trump had sexually assaulted her during a meeting to discuss job opportunities at a Beverly Hills hotel.

She said he "began thrusting his genitals" as she fended off his advances.

Image copyright EPA Image caption Ms Zervos is among several women who have accused Mr Trump of sexual assault, allegations denied by the president-elect

Mr Trump, a Republican, has not filed a lawsuit against any of the women, despite an earlier threat to sue the accusers.

Ms Zervos' lawsuit alleges that the president-elect defamed her by denying her account and accusing her and other women of fabricating sexual assault claims.

She asked Mr Trump to retract his words late last year, but he declined to do so.

Ms Allred said Mr Trump "knowingly, intentionally and maliciously threw each of these women under the bus" and that repeatedly calling them "liars" in public caused distress.

Ms Zervos added that she would be willing to rescind the lawsuit if the president-elect retracts the statements he made and acknowledges his behaviour towards her.

Following her allegations, the Trump campaign released a statement from someone it identified as Ms Zervos' first cousin.

John Barry wrote that he was "shocked and bewildered" by her allegations, insisting Ms Zervos had only previously said "glowing" things about Mr Trump.