In an interview with BBC Radio on Wednesday, Woody Johnson said the chances of a future trade deal between the two countries should not be damaged by false concerns over US farming practices, which he said had been largely driven by the European Union, Presstv Reported.
"I have confidence that whatever way you decide to go that the US and our special relationship will continue and prosper, no matter what," he said.
Asked if that included in a no-deal Brexit scenario, he replied: "In any situation I know that our two countries have to be together in this free world. There's a lot of danger out there, so our relationship is more important now than ever whatever happens with Brexit."
Johnson said in an article published in the Daily Telegraph on Saturday that the UK should ignore "smears" about US farming methods and move away from the EU's "Museum of Agriculture" approach.
Johnson said British consumers had been presented with a false choice. "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," he wrote.
The comments come as Britain prepares to negotiate its own trade deals with the US and other countries after Britain’s departure from the EU set for the end of this month.
Despite huge parliamentary opposition to her Brexit strategy, British Prime Minister Theresa May had indicated that she would be ready to bring Britain out of the EU with no-Brexit deal.