Britain First claims it has received hundreds of new membership applications after Donald Trump retweeted three anti-Muslim videos posted by the far-right group’s deputy leader Jayda Fransen.
Britain First leader Paul Golding also said organisation’s Facebook posts were receiving far more attention in the wake of Trump’s posts, which sparked a Transatlantic row between the White house and Downing Street.
The Prime Minister said on Wednesday Trump was "wrong" to retweet the videos, condemning Britain First as a "hateful organisation."
Trump shot back at Number 10, telling May to “focus” on terrorism in the UK rather than his tweets.
May has rejected calls to cancel Trump’s forthcoming state visit, though the Telegraph reported Thursday that the president’s trip may be dropped amid the fallout from the spat. Downing Street has denied the Telegraph's claim.
Golding, who is facing charges of religiously aggravated harassment alongside Fransen, told the Times: "We have had hundreds of new membership applications and our organic Facebook reach (number of unique users) has increased by hundreds of thousands."
White House press secretary Sarah Huckabee Sanders said Thursday Trump’s tweets had “elevate the conversation” about extremism.
"I think what he's done is elevate the conversation to talk about a real issue and a real threat and that's extreme violence and extreme terrorism, something that we know to be very real and something the president feels strongly about talking about and bringing up and making sure is an issue every single day," she told a White House press briefing.
Speaking on Thursday, May said it was essential to deal with terrorism and extremism "from whatever source they come".
Asked whether she regarded the president as a "supporter and enabler" of far-right groups, May said: "We must all take seriously the threat that far-right groups pose both in terms of the terrorist threat that is posed by those groups and the necessity of dealing with extremist material which is far-right as well.
"I've commented in the past on issues in the United States on this matter. In the United Kingdom we take the far-right very seriously and that's why we ensure we deal with these threats and this extremism wherever it comes and whatever its source."
Britain's ambassador to Washington, Sir Kim Darroch, said he had raised the Government's concerns with the White House.