Britain's Brexit campaigner Nigel Farage said Wednesday he would "hand over the mantle" to Donald Trump as he congratulated the Republican on his US presidential election win.

The interim UK Independence Party (UKIP) leader hailed a year of "two great political revolutions" as commentators immediately drew parallels between the US vote and Britain's decision to leave the European Union.

"I hand over the mantle to @RealDonald Trump! Many congratulations.

You have fought a brave campaign," Farage wrote on Twitter, alongside a video in which Trump publicly hails the eurosceptic, anti-immigrant politician for his success in Britain's June 23 referendum.

Speaking outside the US embassy as Trump's election win became evident, Farage said he was "not particularly surprised" by the outcome.

"The political class is reviled across much of the West, the polling industry's bankrupt and the press just hasn't woken up to what's going on in the world," he told journalists in a video posted on his Twitter account.

"So 2016 is, by the looks of it, going to be the year of two great political revolutions.

"I thought Brexit was big but boy, this looks like it's going to be even bigger."

In a final campaign push in Raleigh, North Carolina on Monday Trump said the US vote would be "Brexit plus plus plus".

Farage threw his support behind the billionaire businessman during the US election campaign, attending a rally in Jackson, Mississippi in August and likening it to his own campaign to leave the EU.

"There are millions of ordinary Americans who have been let down; who have had a bad time; who feel the political class in Washington are detached from them," he told the rally, two months after Britain voted to exit the bloc.

Aaron Banks, a key Farage ally and UKIP's main donor, also took to Twitter to congratulate Trump on his "great result", hailing him the new "Mr Brexit".

"Nigel connected with the working class, Trump did the same. You have no clue of the anger of people who have had enough," he wrote.