Northern Ireland’s Department of Finance raised concerns that Scotland’s same-sex marriage legislation would put same-sex couples in Northern Ireland “in an uncertain legal position”.

The existence of a letter from then-Finance Minister Arlene Foster to the Scottish Government was revealed on Twitter last week by former Scottish Government minister Marco Biagi.

Under the Scottish legislation, a civil partnership entered into in Northern Ireland can be converted into a marriage.

The letter, which was now been published, was sent in relation to the Department’s functions in civil law reform and urged restrictions on the ability to convert civil partnerships entered into in Northern Ireland.

In the letter, Ms Foster wrote that there “is little to be gained from the fact that, post-conversion, the Scottish courts will regard the non-Scottish civil partnership as having ended”.

She continued: “The partnership will continue to exist under the law of the home jurisdiction and the parties will, therefore, have a ‘dual status’, with which they, other parties and other jurisdictions will have to grapple.

“I am sure we would both concede that, from time to time, a policy will produce unforeseen difficulties. However, as policy makers we strive to minimise that possibility and I am sure that neither of us would wish to place same sex couples in an uncertain legal position, which may be difficult and expensive to resolve.

“In this instance, we can achieve legal certainty by restricting the definition of a ‘qualifying civil partnership’ so as to exclude civil partnerships which were entered into in Northern Ireland.”

Ms Foster added: “Secondly, with regard to dissolution, we believe a deemed civil partnership can only exist in Northern Ireland if the Scottish marriage did not result from the conversion of a Northern Irish civil partnership (i.e. a deemed civil partnership cannot exist alongside the original partnership).

“That belief is, however, untested and that is another reason why the definition of ‘qualifying civil partnership’ should be restricted.”