The EU’s top policy chief in the US has warned that the UK can only do a trade agreement with the US when it is fully outside the European Union.

US President-elect, Donald Trump said in an interview on Monday, that he wants to do a trade deal with the UK “very quickly”, while giving his full support for the British decision to leave the EU.

EU Ambassador to the US, David O’Sullivan said the Trump administration’s “idea” of a trade deal with the UK is “interesting” but while the UK remains part of the EU it “cannot conduct its own trade negotiations.

Mr O’Sullivan also reiterated that Ireland can only negotiate the outcome of Brexit as part of the 27-member state block and not in any bi-lateral way, in spite of the fact that the impact of Brexit will be felt in Ireland more than anywhere else in Europe.

“It shouldn’t be forgotten that it was the decision of the UK to withdraw that has created the problem”, not the other member states, he said.

“Unfortunately, there are going to be consequences of the decision that we’re going to try and manage”, but says that there is a “recognition” that Ireland has special concerns which have been acknowledged by European leaders, including lead negotiator for the EU, former Commissioner Michel Barnier.

But ultimately, O’Sullivan confirmed that while Ireland was in a “particular situation”, it was “not unique”, given that several other member states have close trade links with the UK, including many eastern European countries who have thousands of citizens employed there and whose fate and right to remain is unclear.

“Don’t forget that others have stakes in this too” – many of our central and Eastern European partners “have got large numbers working and living in the UK who are very worried about their future”, Ambassador O’Sullivan told Newstalk