European political parties told Facebook they were being forced to take more extreme positions because of the platform's algorithm tweak, a whistleblower claimed.

Frances Haugen, 37, a former Facebook employee, said the social media giant knew it was "tearing our societies apart" by fuelling hate online.

Before she resigned in May, Ms Haugen copied thousands of Facebook documents which she says proved the company knew it was amplifying misinformation and political unrest.

She came forward publicly for the first time in an interview with CBS News in which she accused the company of putting its profits over users' safety.

She singled out the network's 2018 change to the algorithm on its news feed, which caused it to prioritise content that increased user engagement, arguing it made divisive content more prominent.

As a result, European political parties contacted Facebook to complain that they felt compelled to take more extreme positions in order to attract users' attention after the algorithm change.

She said the parties warned Facebook: “You are forcing us to take positions that we don’t like, that we know are bad for society. We know if we don’t take those positions, we won’t win in the marketplace of social media”.

She added that the company's own research had indicated if they made the algorithm "safer" then "people will spend less time on the site, they’ll click on less ads, they’ll make less money.”

Ms Haugen, a data scientist who has worked for companies including Google and Pinterest, said Facebook was "substantially worse" than anything she had seen before.

Sir Nick Clegg, Facebook's head of global affairs and Britain's former deputy prime minister, has disputed the suggestion that the platform promotes political polarisation.

“Our advertisers don't want their content, next to hateful extreme or unpleasant content,” he told CNN, adding that it was "false comfort" to believe technology was driving deepening political polarisation.

The former Liberal Democrat leader, who is reportedly paid around £2.7 million in his new role, has been leading Facebook's defence to the firestorm brought about by Ms Haugen.

The whistleblower first shared documents with US lawmakers andThe Wall Street Journallast month that detailed how Facebook knew its products, including Instagram, were harming young girls' mental health.

Ms Haugen revealed her identity publicly for the first time in CBS' 60 minutes programme on Sunday night, one of America's most-watched news shows.

Ahead of its airing, Sir Nick sent a 1,500-word memo to alert staff to the "misleading" allegations.

In a statement to 60 Minutes, Facebook said: “We continue to make significant improvements to tackle the spread of misinformation and harmful content. To suggest we encourage bad content and do nothing is just not true. If any research had identified an exact solution to these complex challenges, the tech industry, governments, and society would have solved them a long time ago.”

Ms Haugen's revelations have set off a wave of anger from US lawmakers, with senators of both parties comparing Facebook's tactics to the tobacco industry's cover-up of smoking's health effects.

"Instagram is that first childhood cigarette meant to get teens hooked early. Facebook is just like Big Tobacco, pushing a product they know is harmful to the health of young people," said Democratic senator Ed Markey.

Sir Nick called the comparison "profoundly false" during his CNN interview on Sunday.

“I don’t think it’s remotely like tobacco,” he said. “There has to be a reason why a third of the world’s population enjoys using these apps. They do it because they like exchanging their views, their feelings.”