Traveling to the G7 summit in Biarritz, France, the PM said there were “very considerable barriers in the US to British businesses”.
Mr Johnson said he had already spoken to President Donald Trump about his concerns, adding he would do so again when they meet on Sunday morning.
The prime minister will also hold talks with EU Council President Donald Tusk.
“There are massive opportunities for UK companies to open up, to prise open the American market,” Mr Johnson said.
“We intend to seize those opportunities but they are going to require our American friends to compromise and to open up their approach because currently there are too many restrictions.”
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