The French economy minister, Emmanuel Macron, has warned Britain would be “completely killed” in trade talks if the country votes to leave the European Union in June.
Mr Macron, who has been referred to as President François Hollande’s young protégé, made the claim on the BBC’s Andrew Marr show and underlined that France could reconsider border arrangements with Britain.
He also announced on the show that France will go ahead with construction of the £18bn Hinkley nuclear plant, which was announced in October 2013.
He told the programme: "From a political point of view, it's obvious it will be extremely tough vis a vis our people, especially in the north of France, to explain, OK this guy decided to leave but we will keep everything like it was."
Mr Macron said the EU would have to show there were "consequences" of Brexit in its negotiations with Britain. "We have to be very clear that Brexit will have consequences, otherwise that is the beginning of the dismantling. Everybody who disagrees on one or two points will decide to do the same.
"On passports, for sure, on access to the single market, because you will be no more part of the club."
He added: “Your decision to be taken is much more about your role in globalisation. I think UK is not about becoming Jersey or Guernsey. Today, you are strong because you are part of the EU. When you discuss your steel industry with China you are credible because you are part of the EU, not because you are just UK. You will be completely killed otherwise.
“You will never be in the situation to negotiate face to face with the Chinese because your domestic market is not relevant for the Chinese in comparison with their domestic market. EU is the first global domestic market.”
Chancellor George Osborne seized on Mr Macron's comments, tweeting that the minister "makes clear" Britain "would have to pay into EU budget and accept free movement to access single market" after Brexit.
However, Vote leave campaigner Chris Grayling said the claims made by the French minister were a “red herring”. Also appearing on the programme, he said: “This is a great red herring. Let's be clear, the French government, the French interior minister have said very clearly that won't change."
The intervention from Mr Macron comes as Downing Street eagerly awaits the US President Barack Obama’s arrival in the UK this week. He is expected to offer his view to the British public ahead of the upcoming referendum.
