Facebook engineer Brian Amerige has called out the site's political 'intolerance', claiming staff attack colleagues who do not conform to liberal opinions

A senior Facebook engineer has revealed the firm's aggressive 'left-leaning' culture in a damning memo that levels a series of damaging claims against the firm.

Brian Amerige alleges that colleagues 'attack – often in mobs' anyone who is not left-leaning, tear down Trump posters and demand HR investigates anyone who criticizes Islam's human rights record.

Amerige issued his rallying cry in an internal memo that has sparked a group called FB'ers for Political Diversity which has already attracted hundreds of members, and complaints from other members of staff for being offensive to minorities.

It comes after President Trump lambasted social media for 'discriminating against conservatives' and Mark Zuckerberg denied claims of bias while testifying in front of the Senate.

The existence of the memo, and a group called FB'ers for Political Diversity which is acting as a forum for people to air their views, was revealed by the New York Times.

In his missive, Amerige - who has been at Facebook for more than six years - reveals that Facebook staff have torn down posters welcoming Trump supporters, reported those who criticized Islam's human rights record to HR, and 'have made All Lives Matter a fireable offence.'

Amerige said staff are afraid of challenging the liberal culture because they will be personally attacked for it and have their careers ruined (pictured, Mark Zuckerberg testifies to the Senate, when he also faced down questions over conservative bias)

Amerige gives the examples of Palmer Luckey, former Oculus VR boss who was forced out after it emerged he donated money to a group that makes anti-Hillary memes, and Peter Thiel, a member of Facebook's board who regularly faces calls to resign over his support for Trump

'We claim to welcome all perspectives,' he writes, 'but are quick to attack - often in mobs - anyone who presents a view that appears to be in opposition to left-leaning ideology.'

He says employees live in fear of challenging the norm, and claims that HR hears the same complaint often from other members of staff.

'I've personally gotten over a hundred messages to that effect,' he adds.

Amerige then gives the examples of Peter Thiel, an outspoken member of Facebook's board and avid Trump supporter who regularly faces calls to resign.

While Zuckerberg held up Thiel as an example of the company's inclusive nature to concerned Senators, that has not stopped staff targeting him, Amerige says.

Donald Trump has brought the issue of social media bias to the fore in recent weeks, accusing networks of 'discriminating' against conservatives

Trump has repeatedly pledged to tackle the issue, raising the prospect of legal action, but has not laid out his battle-plans yet

Palmer Luckey, the founder of Oculus, a firm which makes virtual-reality goggles that was bought by Facebook, is given as another example.

Luckey was pressured into leaving his job last year after it emerged that he donated money to an organization that spreads anti-Hillary Clinton memes.

All of which, Amerige argues, is damaging to Facebook as it faces attacks from Washington over bias and its effective silencing of conservative voices.

'While the problem isn't unique to us, we are entrusted by a great part of the world to be impartial and transparent carriers of people's stories, ideas, and commentary,' he writes.

'Congress doesn't think we can do this. The President doesn't think we can do this. And like them or not, we deserve that criticism.

'We are blind to and dismissive of what people beyond our walls (let alone even within our walls) think about complex issues that matter.

On Tuesday the President launched a blistering attack on Google for 'rigging' its search results to show only bad news about him, a claim which the tech firm later denied

While the algorithm Google uses to compile its search results is a closely guarded secret, the firm denied that political ideology plays any part in that

'I've been here for nearly 6.5 years and this has gotten exponentially worse in the last 2.'

In order to help solve the problem, Amerige created a group to help share views and promote more political diversity.

The page has already caused staff to lodge complaints with their managers, according to The Times, which added that employees were told the page had not broken any company rules.

Amerige's memo emerged as Facebook COO Sheryl Sandberg prepares to testify about social media's influence over elections to the Senate.

When Zuckerberg testified at a similar hearing earlier this year, he faced down multiple questions - largely from Republicans - about anti-conservative bias, meaning Sandberg will likely face the same queries.

Certainly the question is high on Trump's agenda, as he has spent the last month attacking tech companies and social media specifically for censorship and bias.

President Trump has made conservative censorship online one of his top priorities in the last month, suggesting that it could be even worse than his old foe - 'fake news'

The memo emerged as Sheryl Sandberg, Facebook's COO, prepares to testify to the Senate about social media's influence over the election process

On Tuesday he launched a blistering early-morning attack on Google, accusing the search engine of rigging its results to show only bad news about him.

Later in the day he expanded his attack to include Facebook and Twitter, saying: 'We have thousands and thousands of complaints coming in. And you just can't do that.'

Earlier this month Alex Jones, the controversial host of Infowars, urged Trump to tackle the issue of censorship after he was booted off most social media platforms for 'hate speech'.

At a rally in West Virginia last week, the President said the issue may even be a bigger problem than his old foe, 'fake news'.

He said that 'social media censorship' is 'the new thing' but he'd rather have 'fake news' over people being 'stopped and censored.'

'So we'll live with fake news. I mean, I hate to say it,' he said, 'Because that's by far the better alternative.'