Christopher Stalford pictured with Arlene Foster in December 2016

The statement on Wednesday night said that the Republic of Ireland “has no jurisdiction in Northern Ireland”, and called upon him to observe the terms of the Good Friday Agreement – ‘strand one’ of which provides no role for the Republic in matters of the Province’s internal governance.

Mr Stalford added the DUP will be putting this point to him directly.

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He said the Irish government had publicly declared its support for Sinn Fein’s negotiating position and that this has undermined its credibility when it comes to being neutral (although he did not spell out precisely what exactly the Irish government had said).

He added: “The DUP wants a constructive relationship with the Irish government but it must be founded upon matters of mutual interest and respect between Northern Ireland and the Republic of Ireland.”

The deadline for the talks process is supposed to be 4pm on Thursday.