Peter Robinson denied any wrongdoing over the land deal
First Minister Peter Robinson has denied that he did anything wrong when he bought a piece of land next to his home from a developer for £5.
BBC Newsline reported that the strip of land unlocked access to a development site which included his back garden.
Mr Robinson said the sum paid to Fred Fraser was "nominal" because the land was "useless" to the developer.
He said the BBC was "smearing him" and branded other politicians who have commented on the issue as "liars".
Mr Robinson said the land was not a so-called ransom strip because his garden could have been developed without its purchase.
"I had a free-standing site that could have been developed on its own," he said.
"This piece of ground was of no value to me whatsoever."
Part of Mr Robinson's garden was eventually sold along with several neighbouring gardens.
On Tuesday, BBC Newsline reported that Mr Fraser, who is now deceased, sold the land to Mr Robinson for £5.
The strip was 50 metres from the boundary of their back garden at Gransha Road in Belfast. It was left over from one of Mr Fraser's previous developments.
Mr Fraser knew it was valuable because BBC Newsline talked to a builder who said he tried to buy it, but dropped the idea when Mr Fraser indicated the cost would be a percentage cut of every new house.
When the first minister sold part of his garden to development company Bloomfield Developments for £459,000, Mr Robinson sold the strip for the same £5 he had paid for it 18 months earlier.
In his first interview to address the issues raised in the BBC Newsline report, Mr Robinson accused the BBC of "smearing" him by telling lies.
He said a number of politicians who have commented on the report since its broadcast were also dishonest.
The Ulster Unionist leader Sir Reg Empey and his party colleague Michael McGimpsey have called on Mr Robinson to step aside until he had sought legal advice about his position.
Mr Robinson said: "There is no question of me having any advantage whatsoever as a result of that piece of ground.
"Therefore, Reg Empey, Michael McGimpsey, Trevor Ringland, Jim Allister and the BBC are all liars."
Mr Robinson also dismissed suggestions that he had not properly registered his interest in the strip of land with the authorities at Westminster.
He said that he was obliged only to declare interests up to the value of his MP salary and because the land was only worth £5, he had no need to include it in his interests.
He added: "If I was to declare a piece of land that was bought at five pounds, I would be declaring my burial plot."
A professional valuation carried out for the BBC put the strip's value at upwards of £75,000 when Mr Robinson and his wife obtained it, and at least £220,000 when they sold it.
Mr Robinson also denied that he had not properly declared his involvement in the planning proposal to Castlereagh Borough Council.
Local government legislation says Mr Robinson should have declared an interest if he was present at a meeting where a planning proposal in which he was involved was discussed or due to be discussed.
"There was a schedule which had that item on it and I therefore absented myself from that part of the meeting," Mr Robinson said.
Iris Robinson obtained £25,000 for her teenage lover from Mr Fraser
He did not clarify whether he had declared an interest prior to absenting himself.
In the interview, the East Belfast MP said that Mr Fraser was a "personal friend".
Earlier this year, the BBC Spotlight programme reported that Mr Robinson's wife Iris, then MP for Strangford, obtained £25,000 from Mr Fraser to help her teenage lover open a cafe.
It also reported that when Mr Robinson found out about his wife's financial dealings, he did not report them to the House of Commons authorities, despite being obliged by the ministerial code to act in the public interest at all times.
On Friday, the first minister accused the BBC of holding the Newsline story back until closer to the election to damage his party.
He said the BBC was engaged in "smears and lies" and the corporation had the capability of "making Mother Theresa look like Cruella De Ville".
He added: "People out there are not interested in the BBC's smears."
Commenting on the interview, TUV leader Jim Allister said people "will have been astounded by the manner in which the first minister conducted himself".
"As for his defamatory reference to myself, he can either withdraw it forthwith or face the consequences in another forum," he said.