Legislation allowing Stormont committees to compel witnesses to appear could be used for the first time during the inquiry into the Nama coaching allegations.

Daithí McKay resigned as MLA following reports that, while chair of Stormont’s finance committee, he coached Jamie Bryson ahead of his appearance before the committee.

Mr Bryson went on to make serious allegations to the committee of misconduct on part of then-First Minister Peter Robinson.

Emma Pengelly, current chair of the finance committee, has agreed that Mr McKay - as well as Finance Minister Maírtin Ó Mulleoir - should appear before the committee.

However, Mr McKay has given no indication of whether or not he will co-operate with the committee’s investigation.

Stormont officials, speaking to The Irish News, said he could be compelled to appear under section 44 and 45 of the Northern Ireland Act 1998, which have never before been used.

One Stormont source said: “We’ve never had an investigation as controversial and potentially politically, damaging as this one.

“Add to that the fact the committee is relying on a key witness who is no longer a member of the assembly, a person you would imagine in the circumstances will be a fairly reluctant witness and this may be the first real test of the powers.”