The sugar tax will be an arbitrary burden on the poor which takes no account of the actual make-up of drinks, critics have warned.

The TaxPayers' Alliance said some beverages laden with sugar will be exempt from the levy.

Birkenhead MP Frank Field said the tax would be more useful if it went toward feeding the hungry.

The alliance insists the Budget measure should be junked after it carried out a comparison of 49 different drinks across three areas, fizzy and energy drinks that will be taxed, and milk-based ones, and coffees, that will not.

The survey found that Coca-Cola, with 10.6 grams of sugar per 100 millilitres, will be subject to the levy, but a Starbucks signature hot chocolate with whipped cream with coconut milk, which has 11 grams of sugar per 100 millilitres, will not.

The study also noted energy drinks such as Monster Ori.gin, 11g/100ml, will be taxed, but Tesco chocolate flavoured milk, 12.4g/100ml, will not be.

TPA chief executive Jonathan Isaby said: "It is deeply concerning that the Government has given in to the pressures from the public health lobby and is pushing ahead with this regressive tax which will hit the poorest families hardest.

"The evidence shows that the sugar tax has nothing to do with the sugar content of products, so it is farcical to suggest that this will have any positive impact on people's diet or lifestyle choices.

"This is yet another example of irresponsible meddling from the high priests of the nanny state."

A Treasury spokesman said: "The soft drinks industry levy is a major step forward in our efforts to tackle childhood obesity. Treating obesity and its consequences costs the taxpayer £5.1 billion every year.

"The money from the levy will go towards funding more school sport, and expanding school breakfast clubs.

Mr Field said in a tweet: "Sugar Tax could be made progressive if the proceeds went towards free school meals and fun during the holidays."