Facebook on Thursday removed a campaign ad by United States President Donald Trump and Vice President Mike Pence that featured an upside-down red triangle, a symbol once used by Nazis to designate political prisoners.

The ad which was focused on Trump’s crackdown on far-left group ANTIFA featured a red upside-down triangle with the post. The symbol has been used by the Nazis to designate political prisoners, communists and others in concentration camps, Associated Press reported.

Facebook has removed the ad on the grounds of violating its “policy against organised hate.”

Nathaniel Gleicher, the company’s head of security policy who testified at a House Intelligence Committee hearing on Thursday said the company does not allow hate symbols on his platform unless they are shared with condemnation or context.

“In a situation where we don’t see either of those, we don’t allow it on the platform, and we remove it. That’s what we saw in this case with this ad, and anywhere that that symbol is used, we would take the same action,” he said as quoted by media reports.

The ads remained on the pages of Trump and Pence for at least 24 hours and had hundreds of thousands of views before they were taken down.

Trump’s campaign argued that the ads were about Antifa, and the symbol was used by Antifa which, is why it was included in the ad.

The campaign ads alleged that “Dangerous MOBS of far-left groups” (ANTIFA) were causing mayhem and destroying their cities. The ad called on supporters for Trump’s fight against the civil movement.

"The inverted red triangle is a symbol used by antifa, so it was included in an ad about antifa,"

Tim Murtaugh, a spokesman for the Trump campaign, said in a statement as quoted by BBC.

"We would note that Facebook still has an inverted red triangle emoji in use, which looks exactly the same," he added.

The president said last month that he would designate the anti-fascist group a "domestic terrorist organisation", although legal experts have questioned his authority to do so.

Antifa is a far-left protest movement which is often considered to be a group of activists who are against neo-Nazis, fascism, white supremacists and racism. Following the protests in the US, Trump had alleged that the group had a role to play in these “violent protests.” The US President had further said that he would designate ANTIFA as a terrorist organisation.

The ads have now been taken down. The social media giant has been previously criticised for its decision for limited moderation and fact-checking of political ads announced last year, TechCrunch had reported. Earlier this week the platform had announced that it would allow users to “turn off” all political advertisements on Facebook and Instagram.