The former senior police officer in charge of investigating corruption has revealed that he was ordered to halt an inquiry into Russian money laundering.

Jon Benton, who headed up the National Crime Agency’s international corruption unit, said a more senior official linked to the Foreign Office told him to drop his inquiry.

Mr Benton’s claim is deeply embarrassing for the Government which insists it is clamping down on Vladimir Putin’s cronies who have stashed their wealth in the UK. Mr Benton, a detective superintendent, headed up the international corruption unit (ICU) when it was set up in 2015. He retired last year.

In March 2016, a 37-page dossier alleging money laundering in London by a Russian crime syndicate linked to the Kremlin was handed to him by Bill Browder, a British financier.

Mr Browder has led a near 10-year campaign against the Putin regime after his lawyer Sergei Magnitsky died in a Moscow jail where he had been detained after exposing widespread corruption and theft from his businesses.

Mr Benton, in breaking his silence, told The Telegraph: “Bill Browder had brought this to my attention. I went away and checked our systems and see what we could find to corroborate what Mr Browder was saying.