The DUP leader, Arlene Foster, has said Sinn Féin's Daithí McKay did the right thing by resigning from the Stormont Assembly last week because he had given a witness "lines to take" during an inquiry he was chairing.

The First Minister of Northern Ireland said Mr McKay's actions amounted to attacking the stability of Northern Ireland's institutions and he had stepped way beyond the bounds of what is acceptable behaviour. 

At the time, last September, Mr McKay, was chairing a Stormont Committee inquiry into the purchase of NAMA's Northern Ireland property portfolio. 

Last week he admitted that he had what he said was inappropriate and wrong contact with a witness, Jamie Bryson, before he gave evidence to the Stormont hearing.

Sinn Féin's Máirtín Ó Muilleoir, now Northern Ireland's finance minister, was also a member of the hearing committee at the time.

This week, four DUP Assembly members as well as SDLP, Alliance and Ulster Unionist representatives called on Mr Ó Muilleoir to step aside while the controversy is investigated.

However, Mr Ó Muilleoir insisted he did nothing wrong and that he will not be resigning.

Ms Foster said today that she believes it would be appropriate for the minister to reflect on his position and consider stepping aside, even temporarily, but she accepts it is a matter for him and the Sinn Féin party.

She said the matter has now been referred to the PSNI and to the relevant channels in Stormont and it is important that a full investigation takes place.

The DUP leader believes that the work of the committee, inquiring into the purchase of NAMA properties, has been contaminated by the recent controversy. 

She said she believes the National Crime Agency investigation into the NAMA portfolio is the key work taking place.

Ms Foster is aware of the report on the NAMA file, carried out by the Comptroller and Auditor General. It is now with the Department of Finance.

She said she accepts Minister for Finance Michael Noonan requires time to study the report but looks forward to its publication.