EU Ombudsman Emily O'Reilly has called on the European Commission to publish a key document spelling out all the areas of North-South co-operation under the Good Friday Agreement that are at risk because of Brexit.

The confidential document deals with the so-called mapping exercise, which became a key plank of the Irish Government's strategy to highlight the risks to the Good Friday Agreement.

The mapping exercise highlights the extent to which North-South co-operation relies upon, or is enhanced by, mutual EU membership by both Ireland and the UK.

However, both the European Commission and the British government, which technically had ownership of the document, refused to publish it because the negotiations around the Irish backstop were so sensitive.

A case was eventually taken to the Ombudsman on public interest grounds.

Last night, Ms O'Reilly told RTÉ News there was now "no obvious reason for the [mapping] table not to be published" as the Brexit negotiations had concluded.

Speaking today, the Taoiseach said he wants to see the North-South mapping exercise documenting areas at risk under Brexit "published without delay".

Leo Varadkar said he agrees with the view of Ms O'Reilly. However, he said it is not for the Irish Government to publish the document, as it will be published jointly by EU and UK. 

The mapping exercise was carried out by the British government in the summer and autumn of 2017 at the request of the EU's chief negotiator, Michel Barnier.

When British, Irish and EU officials explored all avenues of North-South co-operation, they discovered there were around 150 areas underpinned by EU law.

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Paragraph 47 of last December's Joint Report between the EU and UK actually refers to the mapping exercise, suggesting it had been completed, but the document itself was never published.

In January a complainant asked the European Commission to publish the document, but the commission refused on the grounds that the document was effectively the property of the UK and that London wanted it to remain confidential.

After several attempts to have the mapping exercise published, the complainant turned to the EU Ombudsman on the grounds that the Brexit negotiations were supposed to be transparent, and that the public had a right to know what areas of North-South co-operation would be at risk because of Brexit.

According to Ms O'Reilly's investigation, the commission argued that "the disclosure of the requested document, which originated from the UK government, against the UK's express wishes, would undermine the trust between the UK and the commission at a sensitive time in the negotiations."

According to her final report, the commission had told the complainant: "Public disclosure of the requested document during the ongoing negotiations, against the opposition of the United Kingdom authorities, at a stage where both sides are still exploring 'flexible and imaginative' solutions, would significantly restrict the European Commission's ability to collaborate with the United Kingdom in an atmosphere of trust and obtain useful information from the United Kingdom authorities."

Ms O'Reilly, who was given access to the document, told the complainant in her report that it covered "a wide array of cross-border topics such as trade, animal health, tourism, the environment, cross-border fraud prevention, the mutual recognition of professional qualifications, and farming."

The EU Ombudsman told the complainant: "There is therefore a very strong case in favour of the right of citizens to know how these issues are being taken into account in the negotiations between the UK and the commission and indeed simply to raise awareness of the extent to which an EU legal and political framework underpins co-operation on many important areas of life on both sides of the Irish border."

In a decision on 9 November Ms O'Reilly concluded, however, that the mapping exercise document was part of a sensitive negotiation between the EU and UK, but that once the negotiations concluded the document should be published.

Both teams of negotiators concluded the Withdrawal Agreement last Monday night.

Ms O'Reilly told the complainant: "It is clear that issues in respect of the border between Ireland and Northern Ireland are proving difficult to resolve in the context of those negotiations."

Her final report states: "The Ombudsman accepts... that the content [of the mapping exercise] gives rise to political sensitivities as it shows - in a single document - the significant extent to which EU membership impacts on North-South co-operation within the remit of the North-South Ministerial Council, an issue which is the subject of ongoing discussions in the context of difficult withdrawal negotiations."

Ms O'Reilly concluded that "the commission's argument that disclosure could foreseeably undermine the negotiations and international relations has some force at the current time."

However, she said she "understands" and "expects" that the commission would "change its position" once the negotiations had been concluded.

Last night Ms O'Reilly said: "The mapping table we inspected shows in comprehensive form the very many elements of cross border co-operation underpinned by EU law - which are factual in nature.

"While the commission - as requested by the UK - declined to release the table in order not to disturb the negotiations, there is now no obvious reason for the table not to be published.

"Indeed, as major decisions in relation to the future of the United Kingdom and its relationship with the EU are now about to be made, there is a strong public interest case for its release."