The International Trade Secretary will say Labour’s vision for the divorce with Brussels will hamstring Britain on trade while negotiators try to seal new deals around the world and ultimately leave the UK worse off than it is now.
His warning comes after Mr Corbyn announced a radical shift in his party’s policy on Brexit.
Labour now says it will back “full tariff-free” trade with the EU27 which would involve membership of a customs union after the UK has cut ties with Brussels.
But speaking in London on Tuesday, Brexiteer Dr Fox will warn such a deal will leave Britain bound by EU rules without any say on how they are made.
And he will say staying shackled to the bloc will “remove the bulk of incentives for other countries to enter into comprehensive free trade agreements with the UK”.
He is expected to say: “As rule takers, without any say in how the rules were made, we would be in a worse position than we are today.
“It would be a complete sell-out of Britain’s national interests.”
“The inevitable price of trying to negotiate with one arm tied behind our back is that we would become less attractive to potential trade partners and forfeit many of the opportunities that would otherwise be available to us.”
Dr Fox is set to cite figures which show 57 per cent of UK exports are now destined for countries outside of the EU, compared to 44 per cent in 2005.
He will say: “We cannot allow the practices and patterns of the past to constrain the opportunities of the future.
“Our approach should not be premised on simply identifying how much of our current relationship we want to keep, but what we need to prosper in a rapidly changing global environment.”
Dr Fox’s address in the capital is part of a series of “Road to Brexit” speeches by Cabinet ministers aimed at reassuring businesses of the UK’s commitment to trade after the split.
His speech will also serve as a warning to Tory MPs tempted to join Labour in voting through an amendment which would force the Government seek a customs union deal with the EU after Brexit.
The Prime Minister will deliver a much-anticipated update on Friday where she is expected to explain the Government’s plans for a system of ”ambitious managed divergence”.
The proposal is understood to be based on a pledge to keep UK standards at the same level as EU rules.
And it is also said to include the creation of a dispute resolution process for when Britain wants to diverge from Brussels.
Details of Mrs May’s plans emerged following a meeting of her Brexit ‘war cabinet’ at Chequers last week.
But the plan was immediately slammed as “pure illusion” by European Council president Donald Tusk.