British Prime Minister Boris Johnson on Saturday urged U.S. President Donald Trump to remove the "considerable barriers" for UK companies seeking to export to the American market, saying they risked impeding a free-trade deal after Brexit.

Speaking as the Group of Seven summit of top nations got underway in Biarritz, Johnson pointed to a string of UK products – ranging from shower trays to Britain's beloved pork pies – that he said were not allowed on the American market.

"There are massive opportunities for UK companies to open up, to prise open the American market," Johnson insisted.

"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," he said.

Brexit advocates, including Johnson, have hailed the ability to strike free trade deals with countries such as the United States as one of the main benefits of leaving the EU. Critics say the terms that Trump will demand are likely to damage the British economy in the long run.

The two leaders are due to meet in person on Sunday morning, which is expected to result in more positive talk about a trade deal, building on a previous promise made by Trump to agree a "fantastic" deal.

Nevertheless, Johnson has used the trip to indirectly criticize Trump, saying a global trade war needed to de-escalate, and that those responsible for rising tariffs could be held responsible for damaging the world economy.

Wary of Britain being seen as what French President Emmanuel Macron called a "junior partner of the United States", the government has also in recent days sought to dampen down the idea of a swift bilateral agreement, stressing that they would not rush into a one-sided deal.

The issue could become a rare bone of contention between Johnson and Trump, with the pair having warm relations dating back to well before the British premier arrived in office last month.

(With input from Reuters, AFP)