Canada's first female prime minister has joined the chorus of women speaking out against Donald Trump as allegations of sexual impropriety continue to mount late in the US election campaign.

"He has described himself as a sexual predator," said Kim Campbell, who became Canada's first female PM in 1993 before losing the post just four months later in a general election.

"The behaviour he has admitted to and celebrated in himself is predation," Campbell said in an interview with the Canadian Broadcasting Corporation early this week.

Trump has been on the offensive against several women who have begun speaking out against the candidate with stories he made unwanted, sexually aggresive advances toward them. The allegations began to mount after a tape of lewd comments in which the candidate describes forcing himself on a married woman and grabbing women's genitals emerged 7 October.

Another tape of out-take footage from a 1992 Entertainment Tonight segment has also just surfaced in which Trump can be heard making lewd comments about an underage girl.

Stories from women in the New York Times and People Magazine published yesterday allege the candidate forced himself on them in aggressive sexual advances in the 1980s and 2005.

The Trump campaign is now demanding that the New York Times retracts its story and has released a letter from Trump's lawyers stating that the piece is "reckless, defamatory and constitutes libel". A statement issued by the Republican's campaign said that "to reach back decades in an attempt to smear Mr Trump trivializes sexual assault".

A man named Gene Folks who was a contestant on the reality TV show The Apprentice, hosted by Trump, in 2010 has also just come forward on Good Morning Britain to talk about the candidate's behaviour.

Folks said the things Trump said about women during the taping of the show were "flat-out disgusting". "Some of the men were blushing that had daughters, they said 'I wouldn't have my daughter around this guy'. That's not any locker room banter that I've been apart of."

In her interview, Canada's former PM Campbell said that "unconsented sexual touching is a sexual assault".

As Canada's Minister of Justice in the 1990s Campbell redrew sexual assault laws in the country, clarifying the definition of sexual assault and introducing a rape shield law.

"It is never consensual for somebody to come up and grab somebody by their private parts or even to kiss them," Campbell said.