ABC, which struck a newsgathering partnership with the BBC in July 1993, outbid its three main rivals for what is being dubbed the scoop of the century. The BBC insisted that ABC paid a "fair market rate" but refused to be specific about the price paid.
As Britons sit down to watch the interview on Monday evening, the programme will simultaneously be broadcast by BBC World and BBC Prime which together reach 46 million homes world-wide.
At a press conference yesterday, the Panorama reporter, Martin Bashir, said the Princess of Wales was given no preferential treatment and insisted that there had been "no paid intermediary... no Mr Big or Mr Fix It" to secure the interview. "I was able to outline the general areas of discussion but no specific questions were given to anyone beforehand," he said.
Mr Bashir insisted that the interview had emerged from more general research into the monarchy and said the BBC had approached the Princess rather than the other way round.
"The invitation came from us. It was not suggested to us by anyone else," he said. "You know and I know that you use first-hand sources if you can," he added.
Mr Bashir, who in the past has presented Songs of Praise, said that because he had never done a royal story before, he had been unaware of the enormity of the scoop.
Mr Bashir was unable to predict what effect the interview would have on the monarchy, saying he was "a professional doing his job".