Chris Smith, the former secretary of state for culture, media and sport, has criticised the decision taken by his successor, Tessa Jowell, to allow the BBC to launch all its planned digital services except BBC3.
Mr Smith was replaced by Ms Jowell in a cabinet reshuffle immediately after the last election and has returned to the back benches.
Speaking publicly for the first time about Ms Jowell's handling of his old job, Mr Smith cast doubt on the wisdom of giving the green light to BBC4, the planned digital channel covering the arts, current affairs and politics.
"I'm not sure I'd have given approval to BBC4 and not BBC3," he said today in an interview with the gay and lesbian website, RainbowNetwork.com.
He said there was a "danger BBC4 will become the sole repository of anything in any way demanding. It might lead to a further slide in the non-populist content of BBC1."
Mr Smith added: "I hope Tessa Jowell is going to be watching that very carefully."
The MP also called for Ofcom, the new communications regulator, to be given greater control over the BBC.
"As we move towards the establishment of Ofcom, I think it, rather than the secretary of state, could be responsible for granting permission to the BBC for new channels and monitoring their performance," he said.
Mr Smith also denied press reports that have put him forward as a possible Ofcom chairman, saying "no one has approached me about it".