It would be unacceptable for Northern Ireland to be in a separate customs territory from the rest of the United Kingdom after Brexit, according to British Prime Minister Theresa May’s spokeswoman. The Financial Times said on Thursday that the European Union had floated a tentative plan which would see Northern Ireland remain in a deep customs union with the bloc while the UK would be in a more “bare bones” customs arrangement. “We have put forward our proposals and the EU is engaging with us but negotiations continue,” Reuters quoted the spokeswoman as saying when asked about the report. “It would be unacceptable for Northern Ireland to be in a separate customs territory.”