Hans-Olaf Henkel said a bad deal for Britain, or even a no deal situation, is Mr Barnier’s “best tool” for avoiding another EU exit.
And Mr Henkel warned Mr Barnier had “tactical and strategic” reasons for wanting to avoid a good deal, a day after the EU’s chief Brexit negotiator sent Britain a warning.
Earlier this week Mr Barnier gloatingly told the Spanish parliament every single EU member state, along with several other regional parliaments, could veto the final Brexit deal.
The following day Mr Henkel told Express.co.uk he believed Mr Barnier was tricking the UK into thinking it could ever secure a good exit deal.
Mr Henkel, a former business chief said he understood but disagreed with the French negotiator’s scheming.
He said: “There is a tactical and strategic reason. He still believes punishing Britain is the best tool to avoid other countries getting the same idea as Britain. I am quite sure that is the case.”
This mindset, he said, was prevalent throughout Brussels.
He said: “His associate in the European Parliament Mr Verhofstadt voices the same sentiment. Totally rubbish.”
Mr Henkel said, as well as punishing Britain with a bad deal, Mr Barnier was also keen on limiting the country’s influence in the EU.
He said a clean break, rather than one in which the UK was still involved in EU matters, was desirable in order to push for more Europe.
Mr Henkel said: “The other reason is strategic. I think they are very interested to let go of Britain.
“Britain was holding up principles laid down in the Lisbon Treaty. Britain is in favour of subsidiarity. Britain is in favour of safer responsibly of accountability for debt but Brussels wants to socialise these.
“Britain is in favour of competitiveness and Barnier wants harmonisation.”
He said he was not confident a deal would ever be agreed between the UK and Brussels.
Mr Henkel said: “No, I am not confident at all. The best deal is if the EU offers Britain a deal which gives Britain what it always wanted – but without Brexit.
“I will do everything possible to avoid Brexit – that would be the best deal.
“Brexit is a lose-lose situation.”
But he said this situation had only developed due to Mr Barnier’s negotiating tactics – and Britain’s mistake in accepting the EU’s guidelines.
Mr Henkel said: “Britain should never have accepted the conditions laid out by Barnier that you can start negotiating on trade only after they have an agreement on how to keep the border in Ireland open.
“That was rubbish. You cannot have a border agreement without knowing what kind of trade deal you have.
“They lost six months of negotiating time. Fortunately now the talks on trade and customs are starting.”
It comes as Brexit minister David Davis was forced to defend on Wednesday a transition deal with the EU that leaves little changed, rejecting criticism that Britain will continue to be a “vassal state”.
Speaking to a parliamentary committee, Mr Davis said Britain’s ties with the EU would “look exactly the same” during what Britain hopes to be two years after Brexit to allow customs, businesses and politicians prepare for a new deal with the bloc