DUP leader Arlene Foster has indicated she is willing to examine details of a Fianna Fáil plan to give Northern Ireland the status of a special economic zone in the wake of Brexit.

However, while Ms Foster’s willingness represents a change of position, the DUP has stressed that the proposal could only be examined in very limited circumstances.

A DUP spokesman said: “Micheál Martin’s idea would need to be tested alongside access to Great Britain. We would not countenance anything that would limit access to the Great Britain market for Northern Ireland.”

The spokesman also said: “The key for us is that Northern Ireland leaves the EU on the same basis as the rest of the UK and there is no border on the Irish Sea.

“Northern Irish dairy farmers should have the same access to Great Britain markets as a farmer in Devon.”

Ms Foster and Mr Martin both delivered keynote speeches at the Killarney Economic Conference at the weekend, which was organised in partnership with The Irish Times.

The Fianna Fáil leader argued that the only credible means of addressing Northern Ireland’s economic needs post-Brexit was for it to become a special economic zone.

Mr Martin suggested such a designation “would threaten no one’s sovereignty”. He said it would enable a means of allowing the free flow of trade North and South, and also east and west.

“It would not in any way undermine the internal market of the UK as it is a model used throughout the world by states seeking ways of developing regions.”

He said those who opposed such a status for the North had used arguments that were not unjustified.

“It is effectively an economic development zone which doesn’t undermine the status of Northern Ireland, and one which provides the basis for respecting the wishes of the majority in Northern Ireland.”

Responding to the proposal during a questions and answers session on Saturday, Ms Foster said she would be willing to hear detail on the special economic zone for Northern Ireland. However, she also emphasised her commitment to the union, a position that was emphasised by her party spokesman on Sunday.

Mr Martin also warned against negotiators rushing to microphones, which was received as an opaque criticism of comments made by Taoiseach Leo Varadkar and Tánaiste Simon Coveney in advance of the phase-one negotiations concluding.

Ms Foster also criticised megaphone diplomacy, which was received in some quarters as a reference not only to Brexit but to the current logjam in negotiations to restore the Northern institutions.