Senior Conservative MPs have dismissed concerns over US food practices such as chlorinating chicken and allowing a certain amount of fly eggs in drinks as “tired old lefty rhetoric” as the government looks to tear away from the hygiene standards expected by the EU to broker a trade deal across the Atlantic.

Former trade secretary Liam Fox and former party leader Iain Duncan Smith took turns to jibe at Labour’s Jeremy Corbyn after he decried US government regulations on acceptable levels of maggots in orange juice.

The US food and drug administration (FDA) says juice with five or more fly eggs or one or more maggot per 250ml should be automatically considered defective.

But Mr Duncan Smith claimed approaches across the Atlantic – such as the management of salmonella through practices like washing chicken meat in chlorine in an attempt to sterilise it – were more effective than those deployed by UK farmers. He accused the Labour leader of “sneering at the standards in the United States".

Speaking in the Commons about the importance of the results of hygiene systems as opposed to practices, he said: “If you look at their standards, when it comes to campylobacterial infection and also salmonella they have fewer deaths per capita than the UK or the European Union. It gets there by different methods and it gets there better than we do, so we should stop sneering."

Bizarre: Boris Johnson drives 'Brexit' digger through boxes Show all 8 1 /8 Bizarre: Boris Johnson drives 'Brexit' digger through boxes Bizarre: Boris Johnson drives 'Brexit' digger through boxes Conservative party leader Boris Johnson drives a JCB through a fake wall POOL/AFP via Getty Images Bizarre: Boris Johnson drives 'Brexit' digger through boxes Prime Minister Boris Johnson during a visit to JCB cab manufacturing centre in Uttoxeter, while on the General Election campaign trail. PA Photo. Picture date: Tuesday December 10, 2019. See PA story POLITICS Election. Photo credit should read: Stefan Rousseau/PA Wire Stefan Rousseau PA Bizarre: Boris Johnson drives 'Brexit' digger through boxes Britain's Prime Minister and Conservative party leader Boris Johnson drives a Union flag-themed JCB, with the words "Get Brexit Done" inside the digger bucket, through a fake wall emblazoned with the word "GRIDLOCK", during a general election campaign event at JCB construction company in Uttoxeter, Staffordshire, on December 10, 2019. - Britain will go to the polls on December 12, 2019 to vote in a pre-Christmas general election. (Photo by Ben STANSALL / POOL / AFP) (Photo by BEN STANSALL/POOL/AFP via Getty Images) BEN STANSALL AFP via Getty Bizarre: Boris Johnson drives 'Brexit' digger through boxes Prime Minister Boris Johnson sits in a cab of a JCB during a visit to its cab manufacturing centre in Uttoxeter, while on the General Election campaign trail. PA Photo. Picture date: Tuesday December 10, 2019. See PA story POLITICS Election. Photo credit should read: Stefan Rousseau/PA Wire Stefan Rousseau PA Bizarre: Boris Johnson drives 'Brexit' digger through boxes Britain's Prime Minister and Conservative leader Boris Johnson drives a Union flag-themed JCB, with the words "Get Brexit Done" inside the digger bucket, through a fake wall emblazoned with the word "GRIDLOCK", during a general election campaign event at JCB construction company in Uttoxeter, Britain, December 10, 2019. Ben Stansall/AFP/Pool via REUTERS POOL REUTERS Bizarre: Boris Johnson drives 'Brexit' digger through boxes A sign made for a visit by Prime Minister Boris Johnson to the JCB cab manufacturing centre in Uttoxeter, while on the General Election campaign trail. PA Photo. Picture date: Tuesday December 10, 2019. See PA story POLITICS Election. Photo credit should read: Stefan Rousseau/PA Wire Stefan Rousseau PA Bizarre: Boris Johnson drives 'Brexit' digger through boxes Britain's Prime Minister and Conservative party leader Boris Johnson drives a Union flag-themed JCB, with the words "Get Brexit Done" inside the digger bucket, through a fake wall emblazoned with the word "GRIDLOCK", during a general election campaign event at JCB construction company in Uttoxeter, Staffordshire, on December 10, 2019. - Britain will go to the polls on December 12, 2019 to vote in a pre-Christmas general election. (Photo by Ben STANSALL / POOL / AFP) (Photo by BEN STANSALL/POOL/AFP via Getty Images) BEN STANSALL AFP via Getty Bizarre: Boris Johnson drives 'Brexit' digger through boxes Britain's Prime Minister and Conservative party leader Boris Johnson reacts as he sits in the cab of a drives a Union flag-themed JCB, after driving through a fake wall emblazoned with the word "GRIDLOCK", during a general election campaign event at JCB construction company in Uttoxeter, Staffordshire, on December 10, 2019. - Britain will go to the polls on December 12, 2019 to vote in a pre-Christmas general election. (Photo by Ben STANSALL / POOL / AFP) (Photo by BEN STANSALL/POOL/AFP via Getty Images) BEN STANSALL AFP via Getty

It is unclear what statistics the former party leader’s claims about salmonella and campylobacter deaths were based on.

Estimates from the US Centre for Disease Control say salmonella accounts for deaths at 420 a year and 1.35 million infections. Deaths through salmonella in the UK, however, are significantly less likely – with the zero salmonella-related deaths in the UK in 2015 and 2016, according to Public Health England.

Meanwhile, the rate of campylobacter deaths in the US stands at approximately 124 per year according to the United States Department of Agriculture. Data held by the UK government found just one related death occurring from 2015 to 2017.

Responding to his party colleague, Dr Fox added: “I hope that my right honourable friend would forgive me if I don’t take too much notice of an anti-wealth, anti-American, anti-trade tired old lefty rhetoric from the soon to be forgotten leader of the opposition."

His comments came after the outgoing Labour leader hit out at Boris Johnson’s withdrawal agreement bill, which passed its second reading a major step towards triggering the Brexit process in time for his 31 January deadline.

Speaking on food standards, Mr Corbyn said: "The choice we now face is between keeping the highest environmental and food standards in order to get a future trade deal with the European Union, or slashing food standards to match those of the United States where there are so-called acceptable levels of rat hairs in paprika, maggots in orange juice.

“If members think that this is a piece of imagination on my part, let me say that when I was first told about it I, too, thought that it could not be the case. I checked it out, and it absolutely is.