Mike Nesbitt has said Sinn Fein’s insistence that the party knew nothing about the current Nama probe scandal is part of a well-worn tradition of denial.
The UUP leader said the republican party’s claim that its hierarchy was left in the dark about exchanges between MLA Daithi McKay and loyalist blogger Jamie Bryson “rings hollow”.
He stressed that a “credible investigation” into the affair is required.
Mr McKay had formerly chaired the Stormont committee which was investigating the Nama property deal.
Whilst heading up the inquiry, he was in contact via the social media service Twitter with Jamie Bryson, a prominent loyalist who was due to give evidence at his committee.
Messages were then exchanged between Mr Bryson, Mr McKay, and another Sinn Fein man called Thomas O’Hara, in which Mr Bryson was given guidance about what he should say when he appeared in front of the committee.
Martin McGuinness was quoted by the BBC on Friday as saying that the notion Sinn Fein’s leadership had known about these Twitter exchanges was “ludicrous”.
On Sunday, Mr Nesbitt said that “ it has been the consistent strategy of Sinn Fein to start with flat denials before the truth is revealed about an incident”.
He said: “History slaps down Martin McGuinness’s statement.
“For a political party, Sinn Fein’s track record is remarkably consistent, to the point it is clearly a strategy to start with a flat denial of involvement or prior knowledge of an event like the coaching of Jamie Bryson.
“Take the murder of Paul Quinn from Cullyhanna in 2007. Gerry Adams’ initial reaction was to deny IRA involvement, claiming it was the work of criminals and that republicans were ‘repulsed’ by the news the young man had been beaten to death.
“But we now know it was an IRA murder.
“So, the deputy First Minister’s words ring hollow, and what we need is a credible investigation.”
Both Mr McKay and Mr O’Hara were suspended from Sinn Fein after the revelations about about the Twitter exchanges emerged.
Although Mr McKay admitted “inappropriate” contact with a committee witness, he denied he had intended to “coach the witness in question with regard to the substance of his testimony”.
Sinn Fein’s press team could not be reached for a comment.
Background to McKay scandal
Stormont’s Finance Committee had been probing allegations of impropriety surrounding the Nama property deal.
This had involved the sale of a package of property loans controlled by Irish agency Nama to a US company. It had been alleged that money from the sale had then been passed on to a politician in Northern Ireland.
When he appeared before the inquiry committee last year, Jamie Bryson made the claim that Peter Robinson was among those who had received money.
Mr Robinson strongly denied this, and said not “one shred of evidence” had been produced to support the claim.