US President Joe Biden is looking to move beyond the old model of free trade agreements and is more geared to today's economic realities and to lessons of the last 30 years, his National Security Advisor Jake Sullivan has said.

Sullivan was responding to a question on visiting British Prime Minister Liz Truss's comment that a free trade agreement (FTA) with the US will take time.

"He (Biden) is looking to move beyond the old model of FTA to a model that is more geared to today's economic realities and the lessons of the last 30 years," Sullivan told reporters at a White House news conference on Tuesday.?

"On a US-UK trade deal, I didn't hear her say that but it's not a surprise to me because free trade agreements take a long time to negotiate. It would be a fair statement of reality about the sheer level of details into which one must go to complete a comprehensive free trade agreement," he said.

That is doubly true about a potential US-UK trade agreement, said the national security advisor in the Biden administration.

Biden will meet the British prime minister in New York on Wednesday.

"About the bilateral meeting tomorrow, I think they will talk about the economic relationship between the US and the UK. They'll talk about the current energy scenario facing Europe as well as the United States," Sullivan said.

"They will talk about the war in Ukraine where Prime Minister Truss has indicated her robust and unwavering support for Ukraine's sovereignty and territorial integrity," he said.?