DUBLIN (Reuters) – The head of the Northern Ireland party propping up British Prime Minister Theresa May’s government on Thursday warned her against any concession in Brexit talks that would create trade barriers between the region and the rest of the United Kingdom.

The Irish government, which has an effective veto over the progress of Britain’s talks to leave the European Union, has suggested that Northern Ireland might impose different regulations, customs or trade rules to the rest of the UK in order to avoid a hard border on the island of Ireland.

“There can be no arrangements agreed that compromise the integrity of the UK single market and place barriers, real or perceived, to the free movement of goods, services and capital between Northern Ireland and the rest of the United Kingdom,” Democratic Unionist Party leader Arlene Foster said in a statement.