Anders Vistisen, of the Danish People's Party, said if the bloc decided to adopt a hard-line approach with Britain, it could drive other member states to leave Brussels too.
The Danish MEP argued any punishment EU leaders planned to dish out would also affect Ireland.
Speaking exclusively to Express.co.uk, Mr Vistisen said: “In the European Parliament there is this sentiment of being angry, being disappointed in the British.
“But let’s be honest, the member states know that we are dependent on each other in security matters, and also in trade matters.
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Anders Vistisen said punishing the UK could drive other member states to leave Brussels
“From a Danish point of view, we would lose one of our biggest trading parties, same thing for Germany, same thing for the Netherlands and Belgium.
“Especially Ireland I think will be a moderating factor here because every time you punish Britain, you punish Ireland also.”
Mr Vistisen said there was a common interest for the bloc to secure a good deal with the UK once the Article 50 process is completed.
The MEP also suggested the idea of “revenge” would be put aside, as he said Theresa May would gain access to the European market “like everyone else”.
Every time you punish Britain, you punish Ireland also
“Ireland is still a member of the European Union and when people think twice about this they’ll [realise] it would not be very wise to push Ireland towards also leaving the European Union,” Mr Vistisen said.
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“I don’t think it’s realistic we are going to give [the UK] such a bad deal but I’m saying that would be the consequence.
“If you really want to punish Britain on trade then [Ireland leaving] would be the consequence.
“If you are punishing someone on trade, you’re punishing yourself, it’s a bit of a crazy narrative, saying ‘you’re not going to gain access to our market’. Not everyone has access to the European market.”
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European Council President Donald Tusk gestures to members of the media as he leaves 10 Downing street after talks with British Prime Minister Theresa May in central London
After last week’s Brexit debate in the European Parliament, Mr Vistisen took to social media to shred Brussels’ demands to Mrs May.
The MEP wrote: “Great Britain should not be punished!!! The EU Parliament has now adopted its position on Brexit… and it has become clear the EU Parliament wants a hard line against Britain.
“They do not want to negotiate a future trade deal with Britain before they have agreed to pay the [Brexit bill], the EU has demanded. [They] have given Spain a veto right in relation to the issue of Gibraltar in the new agreement.”
Mr Vistisen added the European Union was at risk of causing “irreparable damage” to itself and is members, as well as the UK, if it insisted on punishing the British people for Brexit.