The UK or Northern Ireland remaining in the customs union or Single Market would solve the Irish border issue in Brexit talks, according to the Republic of Ireland's European commissioner Phil Hogan.
Speaking to the Observer, Hogan has warned the country would “continue to play tough to the end” in its threats to veto talks on trade unless there are guarantees over the border.
European Council president Donald Tusk on Friday warned that Prime Minister Theresa May had just 10 days to demonstrate progress on the Irish border and other matters before negotiations over a future trading relationship can begin.
The PM has signalled there would be no membership of either the customs union or the Single Market.
DUP leader Arlene Foster, whose party is propping up May's minority government, has said Northern Ireland would not adopt different regulation to that of the UK.
Hogan warned a free trade agreement (FTA) would not be as good as the Single Market.
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“I continue to be amazed at the blind faith that some in London place in theoretical future free trade agreements," he said.
“First, the best possible FTA with the EU will fall far short of being in the single market. This fact is simply not understood in the UK. Most real costs to cross-border business today are not tariffs – they are about standards, about customs procedures, about red tape. These are solved in the Single Market, but not in an FTA.”