WASHINGTON: Britain was seeking to fast-track a crucial post-Brexit trade deal with the United States on Wednesday after new Prime Minister Boris Johnson dispatched his top diplomat and foreign trade minister to Washington.

With Johnson determined to ensure Britain leaves the European Union on October 31, with or without a deal, striking some kind of trade accord with the Trump administration has taken on even greater importance.

The American president, who sees a like-minded leader in Johnson, has said that trade between the two countries could multiply once Britain leaves the EU and spoke to the British prime minister about a deal within days of his taking office last month.

British Foreign Secretary Dominic Raab said he was "delighted" to meet Trump and Vice President Mike Pence.

"We appreciate the President's warmth and enthusiasm for the UK-US relationship. The UK looks forward to working with our American friends to reach a free trade deal that is good for both countries, and cooperating on the common security challenges we face," Raab said in a statement.

Raab was due to hold talks with his US counterpart Mike Pompeo at the State Department and with Trump's National Security Advisor John Bolton.

Britain's International Trade Secretary Liz Truss meanwhile has lined up meetings with top American trade officials.

"Negotiating and signing an exciting new free trade agreement with the US is one of my top priorities," said Truss.

"Having already laid the groundwork, we are fast-tracking this deal so that businesses are able to take advantage of the golden opportunity to increase trade with the US as soon as possible," she added.

"The US is our biggest trading partner and we have more than $1 trillion invested in each other's economies. We want to get formal talks moving quickly."

Truss was due to meet Tuesday with US Trade Representative Robert Lighthizer and Commerce Secretary Wilbur Ross later in the week, US officials said.

After his first phone call with Johnson, Trump told reporters that a bilateral deal with post-Brexit Britain could be "three to four, five times" bigger than current trade and once London is out of the European Union "we could do much more."

"We're working on a trade agreement already," Trump said. "I think it will be a very substantial trade agreement."

- 'Desperate' for a deal -

Johnson, clearly enjoying warmer relations with Trump than his predecessor Theresa May, is hoping that he can clinch a swift deal that can send a message of Britain's ability to strike out on its own.

Trump's apparent enthusiasm for a deal is in marked contrast to the attitude of his predecessor Barack Obama, who said that Britain would be at the "back of the queue" for any kind of trade deal if it left the EU.

But there are warnings that Johnson's willingness to leave the EU without a negotiated settlement with Britain's longtime partners will play into the hands of Trump who prides himself on being a master negotiator.

Trump's good ties with leaders such as Japan's Prime Minister Shinzo Abe have not prevented him from playing hardball in negotiations with allies.

Larry Summers, who was US treasury secretary under President Bill Clinton, said that Britain could not mask the weakness of its hand.

"Look at it from America's point of view: Britain has much less to give than Europe as a whole did, therefore less reason for the United States to make concessions," he told BBC Radio 4 earlier this week.

"You make more concessions dealing with a wealthy man than you do dealing with a poor man.

"Britain has no leverage. Britain is desperate. Britain has nothing else. It needs an agreement very soon. When you have a desperate partner, that's when you strike the hardest bargain."

Last year, the United States ran a $20 billion trade surplus with Britain. The two countries exchanged $262 billion in goods and services, according to the US Trade Representative's office, meaning Britain was America's fifth-largest export market.

Top US exports are financial services and aircraft while British exports include autos and tourism. —AFP