Boris Johnson’s claim that British kipper producers are being hit by EU food safety rules was branded “fake news” by Brussels, after it emerged the regulations had been imposed by the UK government.

And a European commissioner told Mr Johnson that as a potential future prime minister he should “keep a cool head”, warning him: “A fish rots from the head down.”

The Tory leadership favourite dramatically waved a smoked herring above his head as he told Tory activists at a hustings on Wednesday that producers in the Isle of Man were “furious” at the extra costs caused by EU red tape.

He claimed Brussels was demanding that each vacuum-packed kipper sent through the post had to be accompanied by a plastic ice pillow.

And he said that leaving the EU would allow the UK to end this “damaging regulatory overkill”.

But Anca Paduraru, a European Commission food safety spokesperson, told a Brussels press conference: “The case described by Mr Johnson falls outside the scope of EU legislation and is purely a UK national competence.”

Biggest lies told by Boris Johnson Show all 5 1 /5 Biggest lies told by Boris Johnson Biggest lies told by Boris Johnson Made-up quote for The Times Johnson was sacked from The Times newspaper in the late 1980s after he fabricated a quote from his godfather, the historian Colin Lucas, for a front-page article about the discovery of Edward II’s Rose Palace. “The trouble was that somewhere in my copy I managed to attribute to Colin the view that Edward II and Piers Gaveston would have been cavorting together in the Rose Palace,” he claimed. Alas, Gaveston was executed 13 years before the palace was built. “It was very nasty,” Mr Johnson added, before attempting to downplay it as nothing more than a schoolboy blunder. PA Biggest lies told by Boris Johnson Sacked from cabinet over cheating lie Michael Howard gave Boris Johnson two new jobs after becoming leader of the Conservatives in 2003 – party vice-chairman and shadow arts minister. He was sacked from both positions in November 2004 after assuring Mr Howard that tabloid reports of his affair with Spectator columnist Petronella Wyatt were false and an “inverted pyramid of piffle”. When the story was found to be true, he refused to resign. PA Biggest lies told by Boris Johnson Broken promise to boss In 1999 Johnson was offered editorship of The Spectator by owner Conrad Black on the condition that he would not stand as an MP while in the post. In 2001 he stood - and was elected - MP for Henley, though Black did allow him to continue as editor despite calling "ineffably duplicitous" PA Biggest lies told by Boris Johnson Misrepresenting the people of Liverpool As editor of The Spectator, he was forced to apologise for an article in the magazine which blamed drunken Liverpool fans for the 1989 Hillsborough disaster and suggested that the people of the city were wallowing in their victim status. “Anyone, journalist or politician, should say sorry to the people of Liverpool – as I do – for misrepresenting what happened at Hillsborough,” he said. PA Biggest lies told by Boris Johnson ‘I didn’t say anything about Turkey’ Johnson claimed in January, that he did not mention Turkey during the EU referendum campaign. In fact, he co-signed a letter stating that “the only way to avoid having common borders with Turkey is to vote Leave and take back control”. The Vote Leave campaign also produced a poster reading: “Turkey (population 76 million) is joining the EU”

And Vytenis Andriukaitis, food safety commissioner, accused Mr Johnson of spreading “fake news”, as the Isle of Man is not even part of the EU.

Mr Andriukaitis said in a string of tweets: “Boris, the Isle of Man is not bound to the EU ‘pointless and damaging’ red tape in food safety that we are proud of because it protects consumers.

“You omitted to say that the Isle of Man is not in the EU. This packaging – UK competence. Yet another smoke. #fakenews.

“I’ll add one thing. A fish rots from the head down. As potential future PM you need to keep a cool head. So after all, Boris, that ice pillow may turn out to be not so ‘pointless’.”

Mr Johnson told the final hustings of the Tory leadership campaign that the case of the kipper was an example of why the UK was right to want to leave the EU.

“If you want to understand why it is that we must leave the EU and the advantages of coming out, I want you to consider this kipper which has been presented to me just now by the editor of a national newspaper who received it from a kipper smoker in the Isle of Man who is utterly furious because after decades of sending kippers like this through the post, he has had his costs massively increased by Brussels bureaucrats who insist that each kipper must be accompanied by this, a plastic ice pillow,” he said.

“Pointless, expensive, environmentally damaging health and safety, ladies and gentlemen. When we come out therefore, we will not only be able to end this damaging regulatory overkill, but we will also be able to do things to boost Britain’s economy and we will be able to establish an identity as a truly global Britain and get our mojo back.”

As a newspaper journalist in Brussels in the 1990s, Mr Johnson made his name with a series of stories about supposed EU regulations which were repeatedly dismissed by officials as “myths”.

Responding to questions about his new claims, Ms Paduraru said: “Our main priority is the health of our citizens as well as safeguarding the standards in terms of public health and food safety, which are the highest in the world.

“When it comes to the specific case mentioned, while the food business operator has an obligation to meet the microbiological requirements – the safety requirements – to ensure the safety of its food, however the sale of products from the food business operator to the final consumer is not covered by EU legislation on food hygiene.

“This means that the case described by Mr Johnson falls outside the scope of EU legislation and is purely a UK national competence. I hope this is clear, and the rules must be checked with the national authorities.”