The newly-elected French President included a ‘buy European act’ in his manifesto pledge, which would lock the British industry out of the European market.
If such a proposal was adopted by the EU, British-based firms like BT and Serco would be hit hard, according to reports.
The measure is aimed at protecting the Brussels club and ensuring sizeable profit for member states.
Leave campaigners have reacted with outrage at the measures and signalled talks of retaliatory measures.
John Longworth, chairman of Leave Means Leave, told The Times: “The continental Europeans have been playing this game on procurement for a very long time.
“It’s about time we caught up.”
However, Mr Macron’s could fail to get off the floor as the ‘buy European act’ goes against the European Commission which recently pledged that it would “never advocate a buy European only policy”.
Initial projections hint Mr Macron, 39, is set put forward a “tough” stance on Brexit negotiations after he vowed to “defend Europe” just minutes after becoming France’s youngest leader since Napoleon in the French election 2017.
During the build up to the momentous election, Mr Macron called the UK’s decision to unshackle itself from the EU a “crime” and said that Britain had two options, paying EU budgets or a “total exit”.
A staunch EU fan, the centrist chose to appear in front of supporters to the Brussels anthem rather than La Marseillaise.
Addressing his fans, Mr Macron walked across the the Louvre in central Paris to the sound of Beethoven’s ‘Ode to Joy’ the EU anthem, saying: “Europe and the world are waiting for us to defend the spirt of the enlighten everywhere.”
And yesterday Mr Macron’s chief economic advisor Jean Pisani-Ferry said the President-Elect would be a “tough and demanding partner” in Brexit talks.
He said: “He is not the kind of man [who would] agree with the dismantling of the EU.”
Nevertheless Prime Minister Theresa May “warmly congratulated the En Marche movement leader in his victory”.
May 9th, 2017: Express