Despite government assertions that media policy is increasingly transparent, the report argues that it is centralised, opaque and controlled by a small number of advisers and media experts.

Based on interviews with 40 leading media policy-makers, the research, undertaken by Dr Des Freedman of Goldsmith's College in London and funded by the Economic and Social Research Council, argues that the public remains "largely passive" in media policy decisions.

The research will be unveiled on Friday.

Dr Freedman contends that public participation in decisions such as BBC charter renewal - where the Department for Culture, Media and Sport invited licence fee payers to comment directly - hide a reality "where the public remain a largely peripheral force when it comes to influencing questions of media structure".

"Tony Blair's comments about the BBC over the weekend show just how the stakes have got so high with media policy and show the level at which it is influenced.

"The public is occasionally invited to make its voice heard in consultations and opinion polls, but key decisions on, for example, media ownership and concentration or digital switchover are made by government insiders, often in concert with industry lobbyists and sometimes against the wishes of the public.

"This seems to be a process marked less by a commitment to meaningful forms of accountability than it is to ensuring the continuing influence of a restricted number of powerful stakeholders."

How the Communications Act got through

Quoting the example of the 2003 Communications Act, Dr Freedman said it was driven by a "handful" of advisers within Downing Street, "most notably" Ed Richards, now a senior figure at Ofcom.

Despite the high-profile campaign led by Lord Puttnam in the run-up to the legislation, quoting one regulator Dr Freedman says large parts of the Communications Act "went through without any significant debating in committees or on the floor of either house".

He says consultations on UK media ownership - that eventually led to the opening of UK terrestrial broadcasters to foreign ownership - were driven by industry lobbyists, pointing to recently released government papers that show BSkyB representatives met with Downing Street "six times during the short passage of the Communications bill".

"The government ignored the vast majority of the submissions that overwhelmingly opposed the opening up of terrestrial television to foreign companies on the basis, as one commentator put it, 'that this is what the government wanted to do and felt was the right thing to do'."

The government's overt reliance on "hard data" such as economic analysis, even for subjective areas such as public service television, further restricts access for individuals who lack the means to construct such information and thus invariably hand the debate to "experts."

"The fetishising of 'scientific data' is one means of marginalising the public from the public policy process and safeguarding it for the economists, lawyers and executives who are in a prime position to furnish the sort of information that policy-makers are demanding."

Even when the public is invited to contribute to policy, such as during the run-up to the green paper on BBC charter renewal, Dr Freedman argues that these consultations are used merely to justify particular outcomes.

"Key decision makers operate in close ideological conformity with the broad interests of one key constituency - that of business - in a way that structures the parameters of the debate, dictates what forms of participation are most effective and conditions the balance of power in the policy process.

"Public opinion is collected to lend support to policy outcomes but otherwise the process remains largely out of reach for members of the public."