DUBLIN (Reuters) - The small Northern Irish party propping up British Prime Minister Theresa May’s minority government warned her on Tuesday that it would oppose any Brexit deal which it believed undermined the union between Britain and Northern Ireland.

“I am heartened by friends of the Union on both sides of the House (of Commons) and across the United Kingdom who have pledged to stand with the DUP in opposing a deal which weakens the Union and hands control to Brussels rather than Parliament,” DUP leader Arlene Foster said in a statement.

“These are momentous days and the decisions being taken will have long-lasting ramifications. The Prime Minister must win the support of the Cabinet and the House of Commons. Every individual vote will count.”

Earlier, Britain and the European Union reached a draft deal on the terms of the United Kingdom’s exit from the bloc. The issue of the border between British-ruled Northern Ireland and EU member Ireland has been the biggest obstacle in the Brexit talks.