THE BBC has come under fire after booking controversial Leave.EU campaign donor Arron Banks for this weekend’s Andrew Marr show, despite the millionaire being under investigation by the National Crime Agency (NCA).

It was announced on Thursday that the businessman and political donor was being investigated over claims he had hid the source of illegal overseas donations used to fund the referendum campaign.

The NCA are looking at £8 million lent to Better for the Country, the organisation that ran the Leave.EU referendum campaign.

The businessman is set to appear on the BBC’s Andrew Marr show this weekend, where he is expected to respond to the allegations.

BBC politics tweeted: “Sunday Arron Banks will respond to National Crime Agency investigation into campaign funding during Brexit referendum @Arron_banks”

Jo Maugham, of the Good Law Project tweeted: “Good of @BBCPolitics to ensure that no one accused by a regulator of serious criminality and undermining our democracy is left without a major broadcast platform. Up next, Harvey Weinstein on how young actresses were desperate to sleep with him for a career leg-up.”

According to the Electoral Commission, £2.9m of the money donated to Better for the Country was used to fund referendum spending on behalf of Leave.EU and donations to other campaign groups in the middle of the EU referendum campaign.

The Electoral Commission referred the case to the National Crime Agency (NCA) yesterday after its investigation revealed that Elizabeth Bilney, the Leave.EU chief executive had changed her story over some of the donations and loans received by the organisation.

Bilney “originally” reported that Banks was the source of the funds and the money had come from UK-based company, Rock Services.

But the watchdog said she then claimed this loan had not been recorded in Rock Services’ company accounts, and instead appeared in the accounts of an Isle of Man company, Rock Holdings, an investment holding company also owned by Banks.

Banks has denied any wrongdoing, and said that at the time of the donation he got a QC to check that it was permissible under UK law.

He said: “I am confident that a full and frank investigation will finally put an end to the ludicrous allegations levelled against me and my colleagues. There is no evidence of any wrongdoing from the companies I own.

"I am a UK taxpayer and I have never received any foreign donations.”

Theresa May is also under pressure to be come clean about her own dealings with Banks, amid allegations that May blocked an MI5 investigation into the multimillionaire in 2016, when she was home secretary.

The BBC released a statement on Twitter, saying: "There is a strong public interest in an interview with Arron Banks about allegations of funding irregularities in relation to Leave.EU and the 2016 EU referendum. The Electoral Commission has laid out concerns about this in public and it is legitimate and editorially justified for Andrew Marr to question Mr Banks robustly about them."