A politician who held up a sign that said “HE’S LYING TO YOU” as Nigel Farage addressed the European Parliament said he was frustrated by the Eurosceptic politician’s “free pass” to speak unchallenged for three minutes.

Labour's Seb Dance said he had a “screw it moment” when Mr Farage used the opportunity to praise US President Donald Trump and his travel ban on people from seven majority-Muslim countries.

The London MEP’s handwritten sign was broadcast along with Mr Farage’s speech by the BBC, before a clerk told him to put it down.

Ukip later submitted a complaint about his conduct to parliamentary officials, but Mr Dance said he did not regret his actions.

“I sat there frustrated, feeling that the sheer mendacity of Trump’s justifications for his travel ban were not being challenged,” he explained, in a comment piece he penned for The Guardian.

“Time ticked on and Farage’s speaking time drew nearer. I decided I had to try to do something and, noticing the empty chair behind him, I made a sudden decision to grab a piece of paper and scrawl a simple message on it.”

Mr Dance admitted his behaviour had not been particularly “sophisticated” or “parliamentary”, but said he objected to Mr Farage’s argument that the travel ban was a matter for US sovereignty.

“We are not questioning the US’s sovereignty, we are questioning the morality,” he told The Guardian, adding that he was “fed up frankly with nationalist and populist messages being paraded around as if they were the solution to people’s problems”.

Mr Farage is allowed to make an uninterrupted three-minute speech ahead of debates in the EU parliament because he is co-president of the officially recognised Europe of Freedom and Direct Democracy (EFDD) grouping. But Mr Dance said he was angry that the former Ukip leader so often appears to be the dominant British voice in the parliament.

Mr Farage said in his speech that the new US President was simply trying to protect his country from terrorists.

He then appeared to insult other MEPs, saying: “I’m sure as democrats you would all agree that we need to have an open dialogue with the newly elected most powerful man in the world. If you throw that rejection back in my face, then you prove yourselves to be the anti-democratic zealots that I always thought you were.”

He added: “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 welcomed these people into your own homes.”

Mr Dance, who is Labour’s environment and climate change spokesperson in Europe as well as MEP for the UK capital, criticised how the response to a rise in right-wing populism “from many has been to fall over themselves to demonstrate the levels to which we understand this new direction and – terrifyingly – how we will acquiesce to it”.

He said he acted in parliament because it is time to stop and “call out lies where we see them”.

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“No jobs will be created, no industries saved, no community enhanced by scapegoating immigrants for our problems. It’s time to call out those whose diet of hate, division and suspicion will create nothing but misery and poverty,” he said.

The complaint against Mr Dance was submitted by Bill Etheridge, a Ukip MEP, who called his behaviour “pathetic and cowardly”.