However, the plan has been condemned as "unworkable" by the Advertising Association, which warned that it could be illegal. Andrew Brown, the AA's director-general, said: "It sounds ridiculous. We would not be talking about a few agencies working for one government department. It would remove key agencies from the Government's roster."
Ministers are considering an "ethical" approach to Whitehall advertising as part of their drive to tackle obesity. Although they may reject calls to outlaw ads for food and drink aimed at children, the Government is anxious to encourage agencies to stop targeting children.
Brown said: "It would make the job of COI almost impossible. It needs a degree of independence in choosing agencies. This would tie its hands."
Victims could include Abbott Mead Vickers BBDO, which has produced an award-winning anti-smoking campaign for the Department of Health (DoH) but also works for Walkers and Pepsi.
The Government will set out its proposals in a White Paper on public health later this month. Supporters of the plan point out that in the 90s, the DoH refused to employ agencies that worked for tobacco companies.
However, doubts remain as to whether other departments would be prepared to use the Government's entire ad budget as a weapon in the battle against obesity.
Some Whitehall insiders said the ban might be "more of a case of threats rather than action".
- Comment, p48.