Arron Banks, far left, with Donald Trump and Nigel Farage in 2016

This article is the subject of a legal complaint by Arron Banks

The National Crime Agency (NCA) is examining claims that Arron Banks, the businessman who helped fund Brexit, smuggled diamonds out of South Africa.

The NCA has been passed allegations made by Banks’s former business partner that Banks attempted to source black-market gems from Zimbabwe and pretend they had come from his mines in South Africa.

The evidence, collected by South Africa’s organised crime unit, includes a claim that Banks was “dealing with Russians” and trying “to marry . . . illegally gotten diamonds” from other African nations with output from his own struggling mines.

Diamond sales in Zimbabwe are strictly controlled because of corruption and human rights abuses. Russia also exerts a