The US ambassador to the UK has defended his country’s agricultural industry after MPs and campaigners voiced concerns about chlorine-washed chicken and other food products.

On Friday British politicians warned that aggressive US demands for a post-Brexit trade deal could remove “sanitary and phytosanitary” standards in the UK farming industry.

MPs also expressed fears that such a trade deal would lead to spiralling NHS drug costs.

The ambassador Woody Johnson dismissed fears about food standards as “myths”, in an article in The Daily Telegraph.

The billionaire diplomat alleged the debate over a possible deal was “a smear campaign from people with their own protectionist agenda”.

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Mr Johnson also criticised the EU’s “Museum of Agriculture” approach to food standards.

He acknowledged US farmers did wash chicken with chlorine ”to eliminate harmful pathogens”, but claimed they did so to protect “public safety”.

The EU does not allow producers to wash meat with any substance other than water, unless the substance is explicitly approved by the European Commission.

The issue of chlorine-washed chicken has come to symbolise fears about animal welfare and environmental standards after Brexit.

Mr Johnson also defended the use of growth hormones in US cattle production after MPs and campaigners expressed fears about hormone-pumped beef entering the UK.

“The EU chose the moral high ground for its choice not to use growth hormones,” he said.

“But again, there are good reasons American farmers chose a different path.

“They want to produce meat using fewer resources at a lower cost to both the environment and the consumer.”

The diplomat entered the debate a day after Donald Trump’s administration published “negotiating objectives” for a UK-US trade deal.

A storm of criticism followed and Theresa May’s spokesperson attempted to calm fears, insisting the government had ruled out lowering food standards in any future trade deal.

The UK’s National Farmers’ Union (NFU) was among the worried groups reacting to the objectives.

“We should not accept trade deals that allow food to be imported into this country produced in ways which would be illegal here,” said Minette Batters, the group’s president.

Mr Johnson criticised phrases such as chlorinated chicken and hormone beef as “inflammatory and misleading terms”, and said the terms cast US agriculture “in the worst possible light”.

He said he wanted agriculture to be part of a trade deal between the UK and US.

“It is a great opportunity for both of us,” he said.

But the diplomat’s article has attracted further criticism online.

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“The British public benefit from the third most affordable food in the world produced to some of the highest animal welfare, food safety, food hygiene and environmental standards on the planet,” said Stuart Roberts, the NFU’s vice president.

“Not my definition of a museum.”

And Conservative MP Vicky Ford said that the ambassador’s proposals were “bonkers”.

“In the last general election I had more emails from constituents about animal welfare than on all other issues put together,” she said on Twitter.