Northern Ireland First Minister Arlene Foster has rejected calls for a cross-Border inquiry into the £1.24 billion sale of Nama's former Northern Ireland loans portfolio.

Deputy First Minister Martin McGuinness said he supported such an inquiry in the light of further revelations concerning Nama's former Northern Ireland adviser, Frank Cushnahan.

However, Ms Foster said such an inquiry would “not be the appropriate authority” to investigate various issues, including allegations of misconduct surrounding the sale of the loans, known as Project Eagle.

She said she believed the UK National Crime Agency (NCA) was the "appropriate and professional organisation" to deal with any allegations.

Speaking in Antrim on Thursday, Ms Foster said she hoped the NCA would be able to complete its inquiry soon so Northern Ireland "could draw a line under" the controversy.

“To me what’s important is to get the truth of the matter and the way to do that is through the NCA,” Ms Foster said.

US law enforcement agencies are carrying out their own independent inquiries into the transaction.

Secret footage

Earlier this week, BBC Northern Ireland’s Spotlight programme featured secretly recorded footage of Mr Cushnahan allegedly accepting a payment of £40,000 from Northern Ireland property developer

John Miskelly

in a hospital car park in 2012.

At the time, Mr Cushnahan was a member of Nama’s Northern Ireland advisory committee, while Mr Miskelly was a Nama borrower.

Mr Cushnahan has repeatedly denied any wrongdoing in relation to his role with Nama.

An all-Ireland inquiry was first called for by the former head of the Oireachtas Committee of Public Accounts, Fianna Fáil's John McGuinness.

In the light of the Spotlight revelations, Mr McGuinness said a “cross-Border effort must be made to get to the end of this, to get to the truth”.

Martin McGuinness said on Thursday that a cross-Border inquiry should begin once the NCA and any other police investigations conclude.

“What we need is, obviously, the police investigations – whether it be the American ones or on this side of the water – expedited as quickly as possible so we can have full information about what was actually going on,” he said.

All-Ireland investigation

“And then I think we need an all-Ireland investigation, with the administrations north and south co-operating, to, as best they can, get to the bottom of what was happening.”

Northern Ireland Assembly members have called on the NCA to give regular public updates on its investigation.

Disclosure is required from the NCA to ensure public confidence, MLAs said at a special meeting of Stormont’s finance committee on Wednesday.

Meanwhile, Sinn Féin has welcomed the announcement that Nama management will appear before the Oireachtas Committee of Public Accounts (Pac) to answer questions regarding Project Eagle.

Pac member and Sinn Féin TD for Waterford David Cullinane said the Spotlight report raised serious questions for Nama.

“It is imperative that we get answers,” he said.

“The Spotlight programme has enhanced our suspicions that somebody from inside Nama has been giving sensitive information about that body to outside interests for a cash return,” said Mr Cullinane.

He said all transactions involving Nama should be suspended and an independent commission of investigation established.

“Nama assets are public assets and private people cannot make massive profits to the detriment of the taxpayer.”