Mr Burnham said he didn't want to see Jim Royle promoting chocolate bars
The government has indicated it will reject proposals from the European Union to loosen rules on product placement in TV shows.
Culture Secretary Andy Burnham said that product placement could "contaminate" British TV programmes.
Advertisers have been calling for the changes following a decline in revenue from traditional TV adverts.
Changes would see the UK move towards the US system, where product placement is widespread in films and TV shows.
"I can see the benefits of product placement and understand why people feel it is an inevitability given the pressures they are under, but I can also see the costs" Mr Burnham told the Convergence Think Tank.
"There is a risk that, at the very moment when television needs to do all it can to show it can be trusted, that we elide the distinction between programmes and adverts.
"As a viewer, I don't want to feel the script has been written by the commercial marketing director.
"If Jim Royle gets out of his chair for a KitKat, I want to think, 'he fancies a KitKat' - not, 'KitKat my arse!'
"If I thought it was because someone has paid for him to eat one it would change the way I felt about the programme," he added.
The EU recently ruled that member states could choose to allow product placement in commercial TV programmes and films as a revenue source for product companies.
Under the rules, the practice would remain banned in children's programmes, news and documentaries.
Mr Burnham said he would begin a consultation shortly on product placement and was ready to listen to the arguments.
"But here and now I do want to signal that I think there are some lines that we should not cross - one of which is that you can buy the space between the programmes on commercial channels, but not the space within them," he said.
"British programming has an integrity that is revered around the world and I don't think we should put that hard-won reputation up for sale."