Speaking at a conference in London today, Channel 4 director of programmes Tim Gardam outlined the channel's stance on the new public sector digital service for the 16- to 34-year-old market.
Gardam claimed that the BBC's reworked plans for BBC3 become "more difficult to justify the more they are scrutinised".
BBC3 was originally rejected by the Department of Culture, Media and Sport on the grounds that its content was too similar to that provided by the commercial sector.
Culture secretary Tessa Jowell, however, allowed the BBC to resubmit plans for the channel and a public consultation -- which closed on Friday -- was launched.
Channel 4 is upset about the treatment BBC3 is getting, largely because it is being targeted at the same audience that E4 -- Channel 4's commercial digital entertainment channel that it is struggling to turn into profit -- and BSkyB's Sky One are trying to attract.
Gardam said: "The application [for BBC3] includes an independent assessment of the impact of BBC3, which makes it clear that BBC3 is setting out to undermine the ability of Channel 4 to raise the revenue to fund its public service remit."
He added: "It says it aims to take 5% of Channel 4's audience in multichannel homes and 15% of E4's audience. If the BBC's own analysis is correct it aims to take tens of millions of pounds of advertising revenue that Channel 4 spends on its public service broadcasting."
The latest proposal for BBC3, which will have a budget of £90m a year, is said to include plans for just 91 hours of news and current affairs a year, compared with Channel 4's 500 hours. It will also only show 30 hours of educational programming while Channel 4 claims to offer 1,000.
Gardam said that far from being a major injection of money into the UK TV economy, "its impact is likely to reduce programme budgets for other commercial sector broadcasters".
Gardam added that the plans for BBC3 highlighted the need for a single UK content regulator. "As long as the BBC remains outside a single regulated system, I do not believe public service broadcasting has a coherent future," he said.
Channel 4 said Gardam's comments backed up the submission the channel had sent to the DCMS in response to its consultation on the BBC's new plans for BBC3.
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