No 10 aide faces calls to quit over ‘outing’ of Brexit whistleblower

He also alleged through his lawyers that he had been “outed” by No 10 over a relationship he had at the time of the referendum with Stephen Parkinson, a senior figure in the Vote Leave campaign who is now Theresa May’s political secretary.

A Downing Street source made clear that Mrs May continued to have full confidence in Mr Parkinson, a political appointee who is employed by the Conservative Party.

Mr Parkinson said he believed it was inevitable that details of their relationship would become known once Mr Sanni decided to go public with his allegations in interviews with Channel 4 News and the Observer.

However, Chris Wylie, the Cambridge Analytica whistleblower who disclosed the Facebook data breach and a friend of Mr Sanni, said Mr Parkinson’s actions had put Mr Sanni’s family in Pakistan in danger, forcing them to take measures for their own security.

“He was forced to come out to his mum in the middle of the night because No 10 Downing Street decided it was appropriate to out somebody,” Mr Wylie told BBC Radio 4’s Today programme.

“He [Mr Parkison] should resign for outing somebody and endangering his family.”

Mr Parkinson said at the weekend that he was “saddened” by the “factually incorrect and misleading” statements by Mr Sanni and his lawyers.

He said: “I cannot see how our relationship, which was ongoing at the time of the referendum and which is a material fact in the allegations being made, could have remained private once Shahmir decided to publicise his false claims in this way.”

Mr Sanni is set to present further evidence to support his claims at a news conference in London today.

Foreign secretary Boris Johnson – who played a leading role in Vote Leave – has dismissed as “ludicrous” the allegation that the campaign broke election spending rules.

The claims centre around Vote Leave – the officially designated campaign in the 2016 referendum – and its links to the BeLeave group which it helped fund.

Mr Sanni claimed Vote Leave used BeLeave to get around the strict £7m spending limits monitored by the Electoral Commission.

Mr Parkinson and Vote Leave have strongly denied wrongdoing and said the £625,000 donated to BeLeave was within the rules which allowed money to go to other, independent, campaigns.

But Mr Sanni told Channel 4 News: “I know that Vote Leave cheated… I know that people have been lied to and that the referendum wasn’t legitimate.”

The £625,000 was reportedly given straight to Canadian company AggregateIQ – which is alleged to have links to controversial data firm Cambridge Analytica.

Mr Sanni said: “In effect they used BeLeave to over-spend, and not just by a small amount… almost two-thirds of a million pounds makes all the difference and it wasn’t legal.”

Mr Johnson said the Channel 4 News and Observer stories based on Mr Sanni’s testimony were “utterly ludicrous” and Vote Leave “won fair and square – and legally”.

Environment secretary Michael Gove, who was campaign co-chairman for Vote Leave, said the result of the referendum must be respected.

“I respect the motives and understand the feelings of those who voted to remain in the EU,” he said.

“But 17.4m opted to leave in a free and fair vote and the result must be respected. It’s our job now to work to overcome division.”