Hans-Olaf Henkel, an MEP and former President of the Federation of German Industries (BDI), said the EU must make Britain a new offer.
He said Brexit negotiations “are fatal” because there are “expected economic disadvantages on both sides of the channel, most likely to be in the billions”.
The MEP has called on the EU to make the UK more attractive condition especially in areas which made the decisive issues in the referendum.
On the tough Brexit position of the European Parliament, Mr Henkel said: “Everyone moans, but nobody wants to take the first step.”
Brexit news: Mr Henkel called Brexit fatal
The conservative MEP railed against the lack of political will to approach the UK within the so-called EU-friendly factions of the parliament.
This is although many of the deputies in the debate “had deplored the upcoming Brexit”, he said.
Mr Henkel said: “It is now important to make Britain a new offer. For example, the EU should give the British more autonomy on immigration issues. Britain has always been a cosmopolitan country because of its history, so it does not need any regulations and lessons from Brussels.
“I am surprised that the majority of the European Parliament is against Brexit, but nobody in this House really is truly trying to stop the British from leaving.”
Brexit news: The MEP has called on the EU to make the UK more attractive condition
The German is almost a lone politician warning of the potential damage to European industry after Brexit.
He told MEPs Brexit is “lose-lose” for both sides and must be sidestepped for the good of European and the UK.
The Federal Association of German Industry (BDI), of which Mr Henkel was once president, is pressing for a full customs union with the UK after the study revealed a hard Brexit could cost both countries €70billion.
However, Mr Henkel was keen to point out the bigger hit will be felt by the remaining EU27 than it will the British.
Brexit news: ‘Exit from Brexit with a New Deal for Britain and the EU’ was started last year
He said: “By the way, that is €37billion to the remaining European countries.”
The German MEP began his campaign, ‘Exit from Brexit with a New Deal for Britain and the EU’ last year along with Henreich Weiss and Michael Rogowski, three former BDI Presidents in November.
Mr Henkel has repeatedly claimed Brexit will not only damage the UK but also Germany.
He said: “It is so obvious, Brexit will result in a lose-lose situation for both, Britain and the EU.
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“To negotiate a trade agreement with a new partner like Canada or Japan is one thing, but to disentangle trade relationships of thousands of companies which have grown over 40 years is quite another.
“Existing complex logistic chains, supplier and customer relationships would be suffering from Brexit, regardless whether soft or hard Brexit, with and without longer adjustment periods.”
Theresa May said there had been “compromises on both sides” in the push to give “certainty” to businesses and citizens in the EU and the UK about the arrangements for the period immediately after the country formerly leaves the union in March next year.
But the deal is controversial with Brexiteers as it gives the EU jurisdiction over the UK on vital areas of industry such as fishing until the end of 2020.