WASHINGTON -- Joe Biden has played down the chances of brokering a post-Brexit free trade deal with the UK, as he held talks with Boris Johnson at the White House, BBC reported.

Downing Street said its priority was still getting a deal with the US alone.

But the BBC understands that UK ministers are now considering joining an existing North American trade pact instead of pursuing a separate deal.

The two leaders also discussed Northern Ireland, climate change and Afghanistan during the 90-minute meeting.

Downing Street said they "had agreed to continue working towards a future full free trade agreement".

However, Johnson had earlier also downplayed chances of securing a deal with the US before the next general election, saying: "The Americans do negotiate very hard."

Speaking to reporters in the Oval Office before the talks, Biden said the pair would discuss trade "a little bit", adding: "We're going to have to work that through."

A deal would encourage trade by making it cheaper - usually by reducing or eliminating taxes called tariffs.

A source familiar with the government's thinking suggested to the BBC that the UK could negotiate entry into an existing trade arrangement between the US, Canada and Mexico -- known as the USMCA -- set up after former US President Donald Trump tore up its predecessor, NAFTA.

"There are a variety of different ways to do this," the source said. "The question is whether the US administration is ready. The ball is in the US's court. It takes two to tango."