World Heritage body Unesco has rejected claims it backed private developer Seymour Sweeney's bid for a visitors' centre at the Giant's Causeway.
The Giant's Causeway is Northern Ireland's top tourist attraction
It had been reported that Ian Paisley had written a letter to the UK Heritage Lottery Fund in 2003 claiming Unesco backed the developer's bid.
Mechtild Rossler, a senior Unesco official, clarified the situation.
"We don't deal with private developers and I expressed that very clearly to Mr Sweeney," she said.
Speaking on BBC's Good Morning Ulster, Ms Rossler added: "Under the World Heritage Convention, we deal with governments and it's up to the governments to implement the decisions of the World Heritage Committee."
In his letter, Mr Paisley also took the fund to task for not awarding a grant to Mr Sweeney in his bid for the centre.
Sinn Fein's Daithi McKay has called for "full disclosure".
"So that we can not just uncover what has happened but also more importantly so that we can get a new visitors' centre," he said.
"It is clear that it would be a catastrophe to move ahead with private development proposals that would threaten the world heritage status of the site."
The SDLP has called on the first minister to make a statement to the assembly on the controversy.
Assembly member John Dallat, said it could damage the assembly's executive.
"The most recent revelation in the (Belfast) Telegraph has suggested the facts were not as they were," Mr Dallat said.
"The scheme by Mr Sweeney does not have the support of Unesco, does not have the support of the National Trust, does not have the support of the local councils."
Independent MEP Jim Allister said he thought people had been "shocked by the daily revelations over the Causeway debacle".
"How Unesco, the National Trust and EHS can offer professional advice against the private proposal and yet the minister smiles upon it, is unexplained and baffling for most," said the former DUP representative.
The previous visitors' at the Giants Causeway centre burned down in 2000.
The Giants Causeway, renowned for its polygonal columns of layered basalt, resulting from a volcanic eruption 60 million years ago, attracts nearly 500,000 visitors a year.