A Government minister has admitted that only a “significant” tax on sugary drinks would have an impact on UK consumption.

Lord Prior, under-secretary of state at the Department of Health, defended claims that the Government had performed a u-turn on its attitude to a sugar tax when he was grilled by peers this week.

Lord Prior responded to a suggestion by Lib Dem Lord Rennard, who said: “Does the Minister accept that the introduction of a modest sugary drinks tax should be a win-win policy in that, if it works, people would be deterred from consuming those drinks, switch to alternatives and lead healthier lifestyles, and, if it does not work, it would raise money much needed by the NHS to deal with the problems of the obesity and diabetes epidemics?”

Lord Prior said: “I am not sure that the noble Lord is right when he says that a modest tax would have much of an impact; it would have to be a significant tax to have a major impact on the consumption of sugary.”

Asked if the Government should look at the successful campaign to curb the use of tobacco, Lord Prior said: “The Prime Minister has called this the new smoking. Obesity is as important to public health as smoking has been in the past. We have to build a much stronger case among the public at large before we can start to introduce the full range of tax and other measures that we have had for cigarettes and alcohol.”