The UK government has refused to launch an inquiry into its links to financial speculators who are accused of shorting UK assets to profit from a disorderly departure from the EU.

Treasury minister Simon Clarke has tried to rebut claims, from former chancellor Philip Hammond, that Boris Johnson’s hedge fund backers would win “billions of pounds” from a no-deal Brexit.

But several MPs have warned that Boris Johnson faces a conflict of interest, having taken money from investors who have shorted UK companies and could be speculating heavily against the pound.

Answering an urgent question on Hammond’s allegations, Clarke claimed that such theories were “more fit for the tin-foil-hat brigade”. He insisted that the pound should be free to float, and accused critics of “selling this country short”.

Claims that investors who backed Johnson, or the leave campaign, would win billions from the collapse of sterling were simply wrong, Clarke insisted.

And he told several MPs that the best way to avoid a no-deal Brexit was to support efforts to leave with a good deal.

But opposition MPs fear that City speculators are hoping to profit from a disorderly Brexit - as the Treasury’s former top civil servant, Nick Macpherson, has warned. Labour’s Tracey Brabin said it was simply immoral for speculators to profit from the pain and disruption that a no-deal Brexit would cause.