Labour intends to refer Reform UK to the police over allegations the party broke political donation rules by accepting polling financed by an overseas business, it is understood.
Nigel Farage’s party received £32,500 from a US company to fund three surveys commissioned earlier this year, Channel 4 News reported.
The supposed financial backers were actually undercover reporters from investigative group Verbatim, who posed as an American financier and his UK-based son.
Electoral law strictly prohibits foreign companies from providing funds to political parties, including payments intended for research and studies.
The revelations by Channel 4 and Verbatim come amid ongoing scrutiny on funding both Mr Farage and his party have received.
The Reform leader faces a parliamentary investigation into whether he should have declared a £5 million gift from the crypto-billionaire Christopher Harborne given shortly before he was first elected to the Commons in 2024.
Labour intends to report the latest claims Reform may have broken party funding laws to the police, the Press Association understands.
Reform denies any wrongdoing.
Labour Party chairwoman Bridget Phillipson said: “This scandal goes right to the top of Reform UK. Nigel Farage needs to urgently prove today that his top team haven’t broken the law and secretly plotted to undermine our democracy.
“It’s not just Farage’s secret £5 million ‘gift’. Time and again he and his mates think the rules don’t apply to them. The sleaze and scandal now engulfing him and his party isn’t going away – it’s getting worse.
“It’s time to stop the deflections and desperate excuses. Farage and Reform must co-operate with the authorities to establish the truth and prove just how deep this scandal goes.”
Liberal Democrat Cabinet Office spokeswoman Lisa Smart said: “Farage has always behaved as though the rules apply to everyone but him. These new allegations against Reform look like the latest example and must be dealt with swiftly by the authorities.”
Reform said it had “been the target of a hoax perpetuated by foreign-funded, climate change activists posing as would-be party donors.
“The party denies any wrongdoing.
“Reform UK has a robust vetting process for prospective donors approved by the Electoral Commission.”