Pressure mounted on BBC chief George Entwistle as he prepared to face lawmakers today after British Prime Minister David Cameron said the broadcaster had serious questions to answer. Cameron's intervention came as Peter Rippon, editor of the BBC's flagship Newsnight show, stepped aside after admitting he had given an "inaccurate" account of why the broadcaster had axed its own exposé of the alleged abuse of under-age girls by late BBC disc-jockey and television-show host Jimmy Savile. "These are serious questions. They need to be answered," Cameron said of the cover-up allegations. Panorama , another BBC documentary show due to air in Britain last night, is expected to give details of how much information the Newsnight team had on Savile at the time their investigation was shelved. The scandal has engulfed the BBC at a time when it remains under pressure from its critics, who have queried whether it should still be funded via a licence fee paid by the public. Critics argue that the BBC covered up Savile's alleged crimes, which police say took place over six decades and were on an "unprecedented scale". Meirion Jones, the producer behind the Newsnight story, told Panorama he had warned his editor that the BBC was at risk of being accused of a cover-up if it did not run the story. "We weren't asked to find more evidence, or anything like that, we weren't asked to get more people on camera, we were told to stop working on the story," he said in clips broadcast by the BBC. Veteran foreign correspondent John Simpson said the organisation's handling of the case was the worst crisis to hit the BBC in his almost 50-year career. "I don't think the BBC has handled it terribly well," he told the Panorama programme in the clips released by the BBC. "All we have as an organisation is the trust of … the people that watch us and listen to us, and if we don't have that, if we start to lose that, that's very dangerous." The imbroglio has piled pressure on Entwistle to explain what happened. He replaced Mark Thompson, the incoming New York Times Co's chief executive, as BBC director general in August. He will appear before lawmakers amid a growing media clamour for answers. Rippon wrote in his blog that the decision to drop the Newsnight programme was made for editorial reasons, and that the investigation had only focused on possible institutional failings by police and prosecutors. But those reasons have been publicly disputed by the show's journalists, and Rippon stood down to allow an independent inquiry to try to establish the truth. The BBC conceded Rippon's explanation was flawed. "The explanation by the editor in his blog of his decision to drop the programme's investigation is inaccurate or incomplete in some respects," it said. The inaccuracies have fuelled suspicions that BBC chiefs pulled the Newsnight investigation because they did not want it to clash with planned programmes over Christmas commemorating Savile's life as a television celebrity and charity fund-raiser.