Theresa May has been warned by the DUP that the question of using the Irish Sea as a post-Brexit border between Northern Ireland and the rest of the UK is "non-negotiable".

Nigel Dodds, the leader of the DUP in Westminster, has said that talks of a special arrangement for Northern Ireland should be off the table during the Brexit negotiations.

The Irish border issue has been one of the major sticking points of Brexit talks so far as the EU, UK and the Republic of Ireland have struggled to agree how to regulate trade and the movement of people on the island post-Brexit.

Addressing the DUP's annual conference in Belfast, Mr Dodds said: "Make no mistake - for us the integrity of the United Kingdom is non-negotiable.

"If the EU wants to insist on border check points on the island of Ireland that is a matter for them. There will be no internal UK border in the Irish Sea."