Leo Varadkar has told his first EU summit as Taoiseach that it is not too late for the UK to stay within the organisation.
It comes amid heightened security after a foiled terrorist attack in one of Brussels' busiest train stations on Wednesday.
On her way in to today's summit, British Prime Minister Theresa May promised to bring proposals to protect the rights of EU citizens in the UK, and UK citizens living across the EU.
EU leaders however insist that any such issues are dealt with through official channels involving the EU's taskforce and lead negotiator Michel Barnier and UK negotiator David Davis.
Meanwhile, Taoiseach Leo Varadkar said the door was still open for the UK to remain in the EU, a sentiment echoed by EU Council president, Donald Tusk.
"The door always remains open to the United Kingdom," said the Taoiseach. "We don’t want them to leave the European Union or the single market, or the customs union."
Mr Tusk said that in politics "everything is possible" and that a reversal of the Brexit decision would realise a personal dream of his.