The US government was briefed in 2008 that Peter Robinson had orchestrated Ian Paisley's departure from frontline politics, the Belfast Telegraph can reveal.
The allegation is made in a confidential document, reporting on developments in the Northern Ireland peace process, which reached the office of US Secretary of State Condoleezza Rice.
It reported that Mr Robinson is known for his pragmatism, and claims that he "orchestrated the retirement" of Mr Paisley.
The document, which claims DUP MLAs were concerned about First Minister Paisley's relationship with Deputy First Minister Martin McGuinness, supports claims made by the former leader in Monday night's BBC interview.
The claims were denied in two statements from the DUP, who said the timing of Mr Paisley's departure was a matter for himself.
The briefing note would appear to undermine DUP claims that time had diminished his recollection of events.
The document was written in November 2008, six months after Mr Paisley announced he was stepping down as First Minister and DUP leader, and sent by the US Consulate in Belfast to the State Department in Washington.
It provides a summary of political developments in Belfast ahead of a visit by the deputy US Secretary of State, John Negroponte, to the city the following week.
It states: "DUP FM Peter Robinson is known for his pragmatism and shrewd handling of the many diverse elements within the DUP.
"In March, Robinson orchestrated the retirement of the DUP's long-time leader Ian Paisley.
"DUP Members of the Legislative Assembly (MLAs) felt the party was losing support because Paisley appeared to enjoy too much his working relationship with DFM McGuinness."
The note refers to DUP concerns at Ian Paisley Jnr, who stepped down as a junior minister earlier that year amid controversy over his links to a developer.
Similar concerns are said to have been expressed in a survey carried out by special adviser Timothy Johnston, which allegedly questioned Mr Paisley as leader.
Mr Paisley (87), also claimed in the BBC interview he was confronted by Mr Robinson and Nigel Dodds with deadlines for his departure, said to have been issued during a meeting at Stormont Castle in February 2008.
Mr Paisley said: "Nigel Dodds said to me, 'we want you to be gone by Friday'. I just more or less smirked, but Peter said, 'oh, no, no, no, he needs to stay in for another couple of months'."
He added: "I sort of laughed that one wanted two months to prepare the way for himself and the other one – I don't know what he wanted."
Mr Paisley told his wife: "The mighty Dodds wants me to go by the end of this week", with Eileen Paisley replying: "He's a cheeky sod to ask you to do any such thing."
In a statement issued two hours after the programme aired, entitled Statement Of Facts, the DUP said at no point were individuals named in the programme involved in any meeting where Mr Paisley was given an ultimatum to step down.
"Nigel Dodds did not issue an ultimatum that Ian should be gone by Friday nor did Peter Robinson issue any two-month ultimatum. That simply did not happen. Nor did any meeting involving those named by Dr Paisley take place in February as claimed," it read.
"A delegation was charged by Assembly members to express their views on a range of issues to Dr Paisley. This meeting took place on January 31 2008.
"When the delegation relayed the opinions of Assembly colleagues (they did not express their own views) Ian did not accept that the account represented the position of colleagues.
"Dr Paisley asked that a survey of MLAs and MPs be conducted by his Special Advisor to give a general view of his standing in the party. That survey was carried out on February 4 and 5 2008."
The DUP said Mr Paisley sought a meeting with Mr Robinson on March 4, 2008 where he said he intended to retire but that he first wanted to host an International Investment Conference that May.
"As Lord Bannside has said in several interviews and in correspondence, he chose his time of retirement, not anyone else, as has now been suggested," it added.
The second instalment of the BBC's interview with Ian Paisley had an average audience of 258,000. Part two of Paisley: Genesis To Revelation – Face To Face With Eamonn Mallie, was broadcast at 10.35pm on Monday night.
That accounted for a 50% share of the Northern Ireland TV audience.
And it was almost double the figure for the first episode shown last week.