Britain's Prime Minister Boris Johnson speaks to mental health professionals during a visit to Watford General Hospital in Watford, north of London, on Monday. Johnson warned he will not delay Brexit beyond October 31, saying his latest proposals are a last chance to reach a deal, a Downing Street spokesman said on Sunday. Photo: AFP

Britain is looking forward to "taking back control" of its trade policy after it exits the European Union later this month, a government minister told the World Trade Organization (WTO) on Wednesday.

Speaking at a WTO conference, International Trade Secretary Liz Truss said her country was preparing to seize "a golden opportunity."

Britain will be able "to determine our own trade policy for the first time in almost half a century and retake our seat at the WTO as a fully independent, sovereign nation," she said, according to a written version of her speech.

"For those of you worried about where we might have been for 45 years, let me reassure you: Britain is back."

Truss was addressing a closed-door event hosted by the International Chamber of Commerce, attended by British businesses such as BT and mining firm Anglo American, and diplomats.

In a statement released before her address, she claimed "Britain is on the verge of taking back control of its trade policy." "We live in an increasingly protectionist world and it is vitally important - now more than ever - that Britain and other WTO members fly the flag for free trade," she said. 

Her comments came as Brexit talks between Britain and the EU teetered on the brink of collapse just three weeks ahead of the deadline for finding a deal for an orderly departure.

Truss insisted in her address that Britain's exit from the bloc would be beneficial to the country, and also for the international trading system, which currently finds itself under attack.

"We will use our newfound freedom to champion free, fair, rules-based international trade with the WTO at its ­center," she said.

The EU's chief Brexit negotiator Michel Barnier said Wednesday a deal on Britain's withdrawal from the bloc was "very difficult but possible" to achieve before next week's crunch EU summit.

"I think a deal is possible and very difficult but possible," Barnier told Britain's Sky News television, confirming that he will meet his UK counterpart Stephen Barclay on Thursday. "The EU will remain calm, vigilant, respectful and constructive."