The UK’s international trade secretary Liam Fox will spend two days in Washington to discuss the details of a post-Brexit trade deal with his US counterpart Robert Lighthizer.

Removing commercial barriers with the US could generate an additional £40bn ($31bn) in trade with the UK by 2030, Fox said on Sunday, but admitted that discussions would be “difficult”.

“Our exit from the European Union offers an unprecedented opportunity to reshape our independent trading ambitions and build on the already strong trading relationship with our single largest trading partner — the US,” he said in a statement.

Fox will tell lawmakers in Washington on Tuesday that 700,000 US jobs are supported by trade with Britain.

The Department for International Trade added that discussions were expected to focus on “providing certainty, continuity and increasing confidence for UK and US businesses as the UK leaves the EU”.

Under EU rules, member states are not allowed to negotiate free-trade agreements so the talks in Washington are only preliminary.

Adam Marshall, director general of the British Chambers of Commerce (BCC) said that it will not be easy for the UK to secure a good deal with the US.

US negotiators have more experience, he told BBC’s Today Programme:

We’re just getting back into the game of doing this sort of thing after 40 years of doing it via the EU. So I think early on in the process, it would be concerning if the UK were to go up against the US on a complex and difficult negotiation.

Labour Party leader Jeremy Corbyn remains critical of the government’s decision to seek a trade deal with the US, particularly because president Donald Trump intends to withdraw from the Paris climate agreement.

After his two-day trip in Washington, Fox will then travel to Mexico and Texas.