The Republic of Ireland's relationship with the UK will have to change in a post-Brexit Europe, Ireland's EU agriculture commissioner has said.
Phil Hogan said: "Our common interest with the UK in many areas has been a defining characteristic of our EU membership to date."
But this would now be an "enormous mistake" in Brexit negotiations.
Speaking in two national newspapers on Monday, Mr Hogan also said "Brexit is a mess and getting messier".
Writing in The Irish Times, he said: "There is a real risk that Ireland could allow our relationship with Europe to be defined by our relationship with the UK, which would be an enormous mistake in my view.
"Instead, we should have the confidence and direction to recognise that post-Brexit Ireland will need to have in place a wholly different set of relationships with our EU partners."
He also said the country needed to protect its trading ties with the UK and "manage how Brexit impacts on the island as a whole".
In the Irish Independent, he warned that if the UK leaves the EU single market then "a hard border" with Northern Ireland looked inevitable.
He said avoiding such a scenario centred on the EU treating the entire island as a special case and single unit.
The UK voted to leave the EU by 52% to 48% in June's referendum, though Northern Ireland voted to remain by a 56% majority.
Prime Minister Theresa May has said she intends to trigger the official process of leaving by the end of March, meaning the UK will be expected to have left by the summer of 2019, depending on the precise timetable agreed during the Brexit negotiations.