Nigel Farage has been embarrassed by a fellow Member of the European Parliament (MEP) during a speech in which the former Ukip leader defended Donald Trump’s Muslim travel ban.

Seb Dance, a Labour MEP representing London, sat behind Mr Farage and held up a sign reading ‘He’s lying to you’ with an arrow pointing towards him.

Ukip has written to the Parliament's President, Antonio Tajani, to complain about the incident and accuse officials of failing to treat it "with sufficient serious".

Mr Farage was speaking during a debate on the USA's new border controls. He used his speech to praise Donald Trump and attack those criticising the Republican’s ban on immigration to the US from seven Muslim countries.

He said: "It seems to me with all the anti-Trump rhetoric that is coming from everywhere, actually what we are hearing is the true nature of the European project, which is genuine anti-Americanism.

"Trump is motivated by protecting the United States of America from Islamic terrorism whereas what has happened in this room and in governments around Europe is that you have welcome these people into your own homes.

Mr Farage is close to the new US President, having campaigned for him in the weeks leading up to last November's election and become the first British politician to meet with the Republican following his shock victory over Hillary Clinton.

In his speech on Wednesday, the former Ukip leader proposed inviting Mr Trump to speak at the European Parliament, saying: “All of us here say we’re democrats - well here’s a chance to prove it.

“Let us invite President Trump to come here to this European Parliament. I’m sure as democrats you’d all agree that we need to do is have an open dialogue with the newly-elected, most powerful man in the world.

“And if you throw that rejection back in my face then you prove yourself to be the anti-democratic zealots that I always thought you were.”

Nigel Farage's most controversial moments Show all 12 1 /12 Nigel Farage's most controversial moments Nigel Farage's most controversial moments When he unveiled that 'breaking point' poster during the referendum Mr Farage was accused of deploying “Nazi-style propaganda” when he unveiled a poster showing Syrian refugees travelling to Europe under the next “Breaking point”. Users on social media were quick to compare the advert to a Nazi propaganda film with similar visuals and featuring Jewish refugees. The poster was particularly controversial because it was unveiled the morning of the killing of Labour MP Jo Cox Rex Nigel Farage's most controversial moments When he said he’d be concerned if his neighbours were Romanian In May 2014 Mr Farage was accused of a “racial slur” against Romanians after he suggested he would be concerned living next to a house of them. “I was asked if a group of Romanian men moved in next to you, would you be concerned? And if you lived in London, I think you would be,” he told LBC radio during an interview. Asked whether he would also object to living next to German children, he said: “You know the difference” Bongarts/Getty Images Nigel Farage's most controversial moments When he said the EU campaign was won 'without a bullet being fired' Nigel Farage has said the next Prime Minister has to be a Leave supporter AFP/Getty Nigel Farage's most controversial moments When he resigned as Ukip leader and came back days later After failing to win the seat of South Thanet at the general election, Nigel Farage stepped down as Ukip leader – as he had promised to do during the campaign. Days later on 11 May he “un-resigned” and said he would stay after being convinced by supporters within the party. We’ll see how long his resignation lasts this time AP/Matt Dunham Nigel Farage's most controversial moments When he blamed immigrants for making him late Mr Farage turned up late to a £25-a-head ‘meet the leader’ style event in Port Talbot, Wales in December 2014. Asked why he was late, he blamed immigrants. “It took me six hours and 15 minutes to get here - it should have taken three-and-a-half to four,” he said. “That has nothing to do with professionalism, what it does have to do with is a country in which the population is going through the roof chiefly because of open-door immigration and the fact that the M4 is not as navigable as it used to be” Getty Nigel Farage's most controversial moments When he wanted to ban immigrants with HIV from Britain Mr Farage has used his platform as Ukip leader call for people with HIV to be banned from coming to Britain. Asked in an interview with Newsweek Europe in October 2014 who he thought should be allowed to come to the UK, he said: “People who do not have HIV, to be frank. That’s a good start. And people with a skill.” He also repeated similar comments in the 2015 general election leadership debates Getty Nigel Farage's most controversial moments When he defended the use of a racial slur against Chinese people Defending one of Ukip’s candidates, who used the word “ch**ky” to describe a Chinese person, Mr Farage said: “If you and your mates were going out for a Chinese, what do you say you're going for?" When he was told by the presented that he “honestly would not” use the slur, Mr Farage replied: “A lot would” Lintao Zhang/Getty Images Nigel Farage's most controversial moments When he said parts of Britain were ‘like a foreign land’ The Ukip leader used his 2014 conference speech to declare parts of Britain as being “like a foreign land”. He told his audience in Torquay that parts of the country were “unrecognisable” because of the number of foreigners there. Mr Farage has also previously said he felt uncomfortable when people spoke other language on a train Screengrab Nigel Farage's most controversial moments When he said the British army should be deployed to France At the height of trouble at Britain’s Calais border Mr Farage proposed a novel solution. The Ukip leader called for the British army to be sent to France to put down a migrant rebellion. “In all civil emergencies like this we have an army, we have a bit of a Territorial Army as well and we have a very, very overburdened police force and border agency,” he said. “If in a crisis to make sure we’ve actually got the manpower to check lorries coming in, to stop people illegally coming to Britain, if in those circumstances we can use the army or other forces then why not” AFP/Getty Nigel Farage's most controversial moments When he said breastfeeding women should ‘sit in the corner’ Mr Farage sparked protests from mothers after he told women to “sit on the corner” if they wanted to breastfeed their children. “I think that given that some people feel very embarrassed by it, it isn’t too difficult to breastfeed a baby in a way that's not openly ostentatious,” Mr Farage said. He added: "Or perhaps sit in the corner, or whatever it might be” AFP/Getty Images Nigel Farage's most controversial moments When he said the gender pay gap exists because women are ‘worth less’ At a Q&A on the European Union in January 2014 Mr Farage said there was no discrimination against women causing the gender pay gap. Instead, he said, women were paid less because they were simply “worth far less” than many of their male counterparts. “A woman who has a client base, has a child and takes two or three years off - she is worth far less to her employer when she comes back than when she went away because that client base won't be stuck as rigidly to her portfolio,” he said Getty Nigel Farage's most controversial moments When he said he actually couldn’t guarantee £350m to the NHS after Brexit During the EU referendum campaign the Leave side pledged to spend £350 million a week on the National Health Service – claiming that this is what the UK sends to Brussels. Nigel Farage didn’t speak out against this figure and also pledged to spend EU cash on the health service and other public services himself. Then the day of the election result he suddenly changed his tone, saying he couldn’t guarantee the cash for the NHS and that to pledge to do so was “a mistake” Getty

In a statement, Mr Dance said he held up the sign as a way to "protest in the only way I knew how".

He said: "Mainstream politics must be more willing to challenge the nationalists and the populists. They pretend to stand up for people who are suffering but their diet of hate, division and suspicion create only misery and poverty. It's time to stop the nuanced language: they're liars."

"Nigel Farage is regularly treated to free coverage by virtue of being leader of the EFDD [Ukip's European Parliamentary group] and Ukip often use these clips in isolation on social media.

"When debates are time-limited it is impossible to challenge what he's saying, so I protested in the only way I knew how at that point, which was to grab a piece of paper, write a very simple message on it and sit behind Nigel Farage during his usual diatribe."

Mr Trump's ban on immigration to the US from seven Muslim countries has been met with a barrage of opposition from other world leaders, fellow US Republicans and millions of people who have joined protests and signed petitions against it.