The culture and media secretary, Tessa Jowell, faces fresh calls this week from Labour MPs to stand up to the food industry and tackle Britain's obesity crisis by banning food and drink advertising on pre-school children's television.

The pressure on the government is set to increase when the Department of Health publishes a report in the next few weeks which will highlight the decline in physical activity in Britain.

The report by Liam Donaldson, the chief medical officer, found that 70% of British children give up all sports when they leave school, compared with 20% in France.

Ministers in the culture department are reluctant to introduce a ban because they fear lobbying from the advertising industry and allegations of excessive state interference.

Ministers remain focused on increasing children's physical activity, pointing to statistics which show that today's children are 70% less physically active than children were 30 years ago. Ministers also argue that the calorie intake of children in the same period has not worsened.

"We are living in a post-industrial age and physical activity has been collapsing," said one minister. The government is creating more schools sports coordinators and trying to ensure that schools set aside two hours a week for physical activity.

But Debra Shipley, the Labour MP who will reintroduce a bill tomorrow to ban certain types of advertising, said it was "completely stupid" for ministers to pretend that the obesity crisis was caused solely by a lack of physical activity. "This is a crisis that has to be attacked on all fronts at once," she said.

She said Ms Jowell has asked her to provide extra evidence to prove there was a link between obesity and food manufacturers' advertising.

"I took her more; she then said she wanted to wait for a report from the Food Standards Agency," Ms Shipley said.

That report concluded that "advertising to children does have an effect on preferences, food-purchase behaviour and consumption", she added.

"The government has to recognise that on the one side of this argument are the health organisations... and on the other are the food and drink and advertising industry. Tessa Jowell needs to stop waiting and do something as a matter of urgency."

She added: "Little children watching independent television channels are daily bombarded with images of happy little boys and girls eating high fat, high sugar and high salt-content food and drink. They repeatedly hear jingles designed to appeal to them."