Claims by a former republican prisoner that he worked for Sinn Fein in the Irish parliament while still in the IRA require urgent investigation, a DUP MP has said.

Sir Jeffrey Donaldson said the revelations also raise concerns of similar practices at Stormont.

In a new tell-all memoir, Matt Treacy admitted to being in the IRA's Dublin brigade for 30 years until it was disbanded in 2005.

He said this overlapped with him working as an adviser to republican TD Martin Ferris in the Dail.

Mr Treacy previously spent two years on the run as an IRA fugitive before serving four years in Portlaoise Prison.

He took redundancy following the Republic's general election last year after complaining that Sinn Fein had pressured him to hand over part of his salary.

Sinn Fein policy is for members to take an industrial wage, giving the remainder to the party. Mr Treacy resisted this, saying he believed the practice was not followed by all.

"Some were having their mortgages and cars paid and childcare paid for... they were being looked after under the table," he writes in A Tunnel To The Moon: The End Of The Irish Republican Army.

Sinn Fein denied the accusations, calling them "very malicious" and made by a "disgruntled former party member".

It added: "Many Sinn Fein activists make entirely voluntary donations to support the development of the party. This is their choice. Mr Treacy did not make any significant donation to the party over the 14 years he was employed at Leinster House. That was his choice."

Sir Jeffrey, the DUP Westminster candidate and former Lagan Valley MP, called the accusations "very significant".

If true, he said it could mean that "while Sinn Fein have been operating as a parliamentary party in the Irish parliament, they have recruited staff who were also engaged in IRA activities and this may have included spying on other parties and politicians".

"The question arises as to whether similar activities have been conducted in Northern Ireland and I think there is now a need for a full investigation by the Irish authorities into the claims made in this book," he said.

He added that claims of "under the table" payments for staff were "potentially fraudulent" and in breach of Dail rules.

"I think it's legitimate to ask the question if they're operating on a similar 'under the table' arrangements here. This may be something the Assembly authorities will need to examine," he said.

"While Sinn Fein may seek to distance themselves from these claims, they are nonetheless of a sufficiently serious nature to merit proper investigation.

"They can't have it both ways; they are constantly pointing the finger at other parties on the basis of spurious claims and demanding investigations left, right and centre. Therefore they should subject themselves to the same level of scrutiny they insist others are subjected to."

Mr Treacy said he remained a republican at heart, but did not support Sinn Fein or dissident groups.

Belfast Telegraph