Northern Ireland property developer Paddy Kearney is to “vigorously pursue” a case for damages against former Sinn Féin Assembly member Daithi McKay, his solicitor said on Thursday.

Solicitor Paul Tweed said a writ has been issued in the Belfast High Court against Mr McKay for allegedly conspiring with loyalist blogger Jamie Bryson to damage Mr Kearney.

Mr Tweed indicated that others may be sued in relation to claims that Mr McKay, when he was chairman of the Assembly’s finance committee, coached Mr Bryson on how to make allegations against Mr Kearney and also against the then DUP First Minister Peter Robinson.

Mr Kearney is seeking exemplary damages against Mr McKay for alleged libel, conspiracy, malfeasance in public office and falsehood.

Said Mr Tweed: “We have been instructed to vigorously pursue this litigation and are actively considering further legal proceedings against other potential parties in relation to what have been totally unfounded and unjustified personal attacks on our client’s hard earned reputation earned over many years, and in the process supporting and creating much needed employment for the Northern Irish economy.”

Mr McKay said on Thursday that he was making “no comment at this moment in time”.

The case relates to how in September 2015 Mr Bryson gave evidence to the Stormont finance committee about the £1.2 billion sale of Nama’s huge Northern Ireland property portfolio to US investment giant Cerberus.

Mr Bryson in the course of that evidence claimed that Mr Robinson and four other men, whom he named, financially were to gain from an alleged £7 million “kickback” as a result of that sale.

He also separately claimed that Mr Kearney - who was not named as one of the five who allegedly gained from the Cerberus purchase - was assisted by Mr Robinson in a “sweetheart deal” to refinance his Nama-controlled loans after they were bought by Cerberus. Mr Robinson rejected the allegations.

In November, Mr Kearney appeared before the finance committee to deny the claims and to say he was the victim of “unfounded and unsubstantiated allegations” and “unwarranted personal attacks”.

Mr Kearney was one of the so-called Maple 10 who bought shares in the troubled Anglo Irish Bank during the financial crash. His company Kilmona owns the boutique Ten Square Hotel in central Belfast and he is involved in multi-million pound plans to construct new office space in the city.

While Mr Bryson’s allegations were made under privilege at the Assembly committee, it is understood that Mr Kearney and his legal team are partly basing their case on the claim that Mr McKay allegedly was involved in a wider conspiracy with Mr Bryson.

This relates to communications between Mr McKay and another Sinn Féin member with Mr Bryson on how he might present his allegations against Mr Robinson and others at the September 2015 meeting of the Assembly finance committee. Details of this alleged coaching emerged in August this year.

While Mr McKay denied any conspiracy claims in August he stood down as an Assembly member and was suspended by Sinn Féin. Mr McKay last week disclosed that he has resigned from the party.