Hillary Clinton on Monday denounced President Donald Trump as a 'danger to democracy' and said she would back any candidate taking on Trump.

Iran Press/America: 'I will support the nominee of our party because I think that our current president is a clear and present danger to democracy and to our future,' she told journalists at the Berlin film festival, where a new documentary about her life was being screened.

Yet she refused to endorse any specific candidate, saying she would 'leave that to the voters'.

The documentary has grabbed headlines for caustic remarks Clinton makes about Sanders, who took pole position in this year's race with a key win in Nevada on Sunday.

'Nobody likes him, nobody wants to work with him, he got nothing done. He was a career politician,' she says in the four-part film.

She defended the comments on Monday, saying: 'Politics is a contact sport, people say all sorts of things. They've certainly said all sorts of things about me.'

The former US secretary of state, who beat Sanders in the primaries but ultimately lost to Trump at the 2016 US presidential election, said the new documentary would tell 'the real story' of her political career.

'It shows the story of how hard political change is. That is an important story, because in a democracy, if you get discouraged and you give up on it, that leads to voices of extremism promising all sorts of things.'

She claimed it showed her political successes in the face of 'tremendous opposition, including being burned in effigy and being threatened'.

Clinton remains a divisive political figure.