The leader of the Democratic Unionist Party (DUP) raised the stakes over the Brexit Northern Ireland border protocol on Thursday when he warned his party would walk away from power-sharing arrangements in Stormont. Sir Jeffrey Donaldson delivered a keynote speech at the La Mon hotel in Belfast, telling listeners that "as leader of the DUP, I am not prepared to lend my hand to a protocol which so fundamentally undermines the Union and the economic integrity of the United Kingdom and Northern Ireland’s position in it".

       Sir Jeffrey said Northern Ireland needed "significant and substantial changes that can meet the seven tests that we set out" to make the border protocol work:

       READ MORE: Brexit latest: DUP leader blasts diverting trade from GB ally

       Sir Jeffrey said the DUP could quite Stormont altogether and trigger a fresh election "within weeks" if the above tests aren't met.

       He made it clear his party would now boycott most north-south ministerial meetings.

       He said such relations could not be "business as usual" while links with Great Britain were damaged.

       Sir Jeffrey said his party's ministers would resign from their post rather than implement further border checks on goods entering Northern Ireland from the rest of GB.

       He said: "We are totally opposed to the protocol as it presently exists. We will neither accept it nor will we work it.

       "In my assessment, the time frame for resolving issues can be measured in weeks and not months or years,” he said.

       “If, in the final analysis, those who are democratically elected by the people of Northern Ireland lack the power to prevent such checks, and the protocol issues remain, then the position in office of DUP ministers would become untenable.

       “Let me be clear: if the choice is ultimately between remaining in office or implementing the protocol in its present form, then the only option for any unionist minister would be to cease to hold such office,” he said in a speech in Belfast.

       He said the UK’s approach to “limit” the protocol was “doomed to fail” and it “is far better that we grasp the nettle now and have the matter settled once and for all”.

       This is a major political move for Sir Jeffrey, who took over from Arlene Foster as party leader in the summer.

       The DUP has slumped in the polls since, with rival unionist parties picking up support.

       The speech comes as the European Commission Vice President Maro？ ？ef？ovi？ begins a two-day visit to Northern Ireland during which he will hold talks with political and business leaders in an attempt to understand what impact the border protocol is having.

       The protocol was part of the UK government's Brexit deal with the European Union.

       The protocol is intended to keep Northern Ireland aligned with the EU's single market for goods to ensure free trade across the Irish border.

       However, it has led to additional checks on goods being traded across the Irish Sea, which has drawn criticism and protests from unionists who see it as equivalent to a border between Northern Ireland and Great Britain.

       Earlier this week the UK government indefinitely extended grace periods on border checks which it said was necessary to create space for further talks with the EU.