The Prime Minister has vetoed taxing sugary drinks and food but has not read a report detailing the evidence.
A spokesman for the Prime Minister said David Cameron was not in favour of a tax, believing there were other measures to drive down childhood obesity.
"The Prime Minister's view remains that he doesn't see a need for a tax on sugar," the Number 10 spokesman told reporters.
Mr Cameron's stance puts him at loggerheads with campaigning TV chef Jamie Oliver, who has said he is "ready for a fight" with Government on the issue.
The admission comes as a controversial report from Public Health England (PHE) was finally published suggesting a tax of up to 20% on sugary drinks and food would cut consumption.
The report says a levy would tackle the obesity crisis by curbing demand for unhealthy food and drinks.
The study was originally shelved by Health Secretary, Jeremy Hunt, who planned to publish it alongside a Government strategy on tackling obesity later this year.
But a row occurred between the Government, PHE and MPs on the Commons health committee over claims it was suppressed, leading PHE to finally release it.
The report calls for efforts to "reduce and rebalance" the number and type of price promotions on foods and to "significantly reduce opportunities to market and advertise high-sugar food and drink products to children and adults".
It said food retail price promotions "are more widespread in Britain than anywhere else in Europe" and "higher sugar products are promoted more than other foods".
The report, called Sugar Reduction: The Evidence For Action, warns that average sugar intake is 12% to 15% of people's energy intake instead of the 5% Government advisers say it should be.
For school-age children, sugar is 14.7% of all calorie intake and 15.6% for teenagers.
The PHE report said it "would seem logical" that a "sugar tax" of 10% to 20% would lead to a reduction in consumption, though it stressed some of the evidence on the issue was limited.
"Research studies and impact data from countries that have already taken action suggest that price increases, such as by taxation, can influence purchasing of sugar-sweetened drinks and other high-sugar products at least in the short term with the effect being larger at higher levels of taxation," it said.
It said a recently introduced 10% tax on sugary drinks in Mexico, which has escalating rates of obesity, had resulted in an average 6% drop in purchases in the first few months.
But it said: "While this is significant, its impact is small when compared to marketing strategies such as end of aisle display locations, which have been seen to increase sales of carbonated drinks by as much as 50%."
The report pointed to the main sources of sugar in children's diets as being soft drinks, table sugar, confectionery, fruit juice, biscuits, buns, cakes, pastries and puddings and breakfast cereals.
Soft drinks (excluding fruit juice) are the largest single source of sugar for children aged 11 to 18, with those children who have them consuming the equivalent of one can of sugary drink every day.
Soft drinks provide 29% of daily sugar intake, on average, for this age group as a whole, the report said.
In other recommendations, the report said steps should be taken to create a clear definition of what high sugar foods are.
It also calls for reformulating products with less sugar, as has happened with salty foods.
Attacking price promotions in supermarkets and other outlets, the report said: "Price promotions increase the amount of food and drink people buy by around one-fifth.
"These are purchases people would not make without the in-store promotions."
Writing in the Daily Mail earlier, Oliver said he had based his arguments on evidence from doctors and scientists, despite industry perhaps presenting him as a "TV chef who has got too big for his boots".
He added: "In my meetings with him (Mr Cameron) on the subject, I've outlined my own experiences of seeing just how devastating too much sugar can be."
The Number 10 spokesman defended Mr Cameron's position, saying: "The Prime Minister's view on this is pretty clear - he very much sees that it is really important for us to tackle childhood obesity."
Proposed measures such as restrictions on advertising unhealthy products to children or lowering sugar content in food and drinks would be taken into account as the strategy was drawn up, he said.
But he added: "The Prime Minister's view remains the same, that he does not see the need for a tax on sugar, but that it's important to remember that that is not the only part of this debate, that there are a large number of different elements to it... The Prime Minister thinks there are more effective ways of tackling this issue than putting a tax on sugar."
The spokesman confirmed that the PM had not read the PHE report before forming his view on the sugar tax: "I don't believe he's read that specific report, but obviously all of the evidence and all of the reports on this wide-ranging set of issues will all be taken into account. There are lots and lots of pieces of evidence within this debate."