Junior Stormont Minister Ian Paisley Jnr was last night facing calls to spell out the full extent of his lobbying on behalf of prospective Giant's Causeway centre developer Seymour Sweeney.
The DUP politician has been a champion of a number of Mr Sweeney's projects, particularly the controversial Causeway project.
Mr Paisley Jnr could not be contacted for comment last night, but continues to defend his right to speak up for a businessman in his constituency.
The Belfast Telegraph has learned that the MLA gave evidence at a 2005 planning appeal in support of a housing development proposed by Sweeney, who is also a DUP member.
He has also supported him publicly on a contentious pub development project and a legal challenge against Department of the Environment development framework, the Northern Area Plan.
Mr Paisley Jnr confirmed yesterday to the BBC that he had lobbied for a driftnet licence on behalf of a north coast fisherman whose crew included Mr Sweeney and two of his relatives. The politicians said he had done so because he believed in the case. He also confirmed he had been lobster fishing with the developer.
The DUP has faced controversy since its Environment Minister Arlene Foster last week announced that she was "of a mind" to grant planning permission to Mr Sweeney's Causeway visitor centre blueprint.
SDLP MLA John Dallat last night said: "It's time for the Minister to make a full disclosure on his lobbying on behalf of his party colleague."