The US should join the back of a queue for a post-Brexit trade deal if it thinks its “woefully inadequate” and “backward” animal welfare and food safety standards will be accepted in Britain, the former farming minister George Eustice has said.

Eustice, a leading Brexit supporter who resigned from the Department for Environment, Food and Rural Affairs last week, said signing any deal that allowed a reduction in food standards would be a mistake, as it could “give free trade a bad name”.

His remarks are a rebuttal to Woody Johnson, the US ambassador, who last week invited the UK to drop its opposition to certain practices such as the use of hormones in beef and chlorine washes in chicken when considering a trade deal.

The issue is a contentious one within the UK government as Michael Gove, the environment secretary, has insisted food and welfare standards will be maintained, but Liam Fox, the trade secretary, has defended the safety of chlorine-washed chicken.

If the US insists on chlorinated chicken, it can forget a trade deal Read more

Writing for the Guardian, Eustice said the UK has a “sophisticated and discerning” market for food but agriculture in the US “remains quite backward in many respects”.

“Their livestock sectors often suffer from poor husbandry which leads to more prevalence of disease and a greater reliance on the use of antibiotics,” he said. “Whereas we have a ‘farm to fork’ approach to managing disease and contamination risk throughout the supply chain through good husbandry, the culture in the US is more inclined to simply treat contamination of their meat at the end with a chlorine or similar wash.”

He said the situation in relation to animal welfare was even worse, as “legislation as regards animal welfare is woefully deficient”.

Food fight: doubts grow over post-Brexit standards Read more

“There are some regulations governing slaughterhouses but they are not as comprehensive as ours,” he said. “As far as on-farm welfare legislation is concerned, there is virtually nothing at all at a federal level and only very weak and patchy animal welfare regulations at a state level, predominantly in the west coast states. There is a general resistance to even acknowledging the existence of sentience in farm animals which is quite extraordinary.”

Eustice, a longstanding Brexit supporter, resigned from the government last week, saying Theresa May’s decision to allow a vote on delaying article 50 would be “the final humiliation of our country”.

He said he was strongly supportive of the UK striking trade deals after Brexit but they should demand that suppliers meet British standards, highlighting a Conservative manifesto commitment to do so.

“If the Americans want to be granted privileged access to the UK market, then they will have to learn to abide by British law and British standards, or they can kiss goodbye to any trade deal and join the back of the queue,” he said.

He said trade deals should be an opportunity to “project British values of kindness and compassion” rather than allow them to be undermined.

Johnson, who has been ambassador since 2017, set out the US position on a post-Brexit trade deal in the Telegraph last week, saying it was a myth that chlorine-washed chicken and hormone-pumped beef were bad.

“You have been presented with a false choice,” he wrote. “Either stick to EU directives, or find yourselves flooded with American food of the lowest quality. Inflammatory and misleading terms like ‘chlorinated chicken’ and ‘hormone beef’ are deployed to cast American farming in the worst possible light.”

Johnson described using chlorine to wash chicken as a “public safety no-brainer” and insisted it was the most effective and economical way of dealing with “potentially lethal” bacteria.

He said the EU was a “museum of agriculture” and its “traditionalist” approach belonged in the past.