It was conducted by Gemma Bridge, of Leeds Beckett University, with Professor Raman Bedi, professor of transcultural oral health at King's College, London and England's former chief dental officer.
Bridge said breastmilk was sweet and high in energy but the sugar it contained - as much as 7g - was naturally occurring lactose which was specific to the needs of the growing infant.
"Conversely, infant formula milks have a standardised make-up and contain added sugars such as corn syrup which are added during production and are not found in breast milk," she said.
"This is bad for babies because high consumption of added sugars may contribute to tooth decay, poor diet and lead to obesity in children."
Bridge said the use of sweeteners not only encouraged more mothers to buy the products because babies liked them but also risked creating a preference for sweet tastes at a young age which could have a detrimental effect on future eating habits.
Data compiled by the researchers showed the highest was Abbott's toddler drink go and grow for 12 months-plus, which had 9.8g per 100ml.
It was followed by SMA's Pro Growing up Milk Formula for 12 months-plus (8.2g/100ml) and HiPP's organic follow on milk ready (8.1g/100ml) for six to 12 months.
The study, published in the British Dental Journal, said some manufacturers of formula milk also appeared to be flouting restrictions on the use of images of infants or graphics to promote and idealise their use.
"The World Health Organisation's International Code of Marketing of Breastmilk Substitutes stipulates that infant formula products should not be promoted over breastfeeding," Bridges said.
"But we found that many of the formulas had labels that included images of infants or cute toys of animals, presumably designed to entice caregivers into buying."
"Such findings are not unsurprising as there is evidence that harmful marketing strategies have been used extensively by infant formula and follow-on milk manufacturers."
The baby milk manufacturers deny the claims.
A spokesman for the British Specialist Nutrition Association said: "UK formula is already highly regulated and for infants where parents are unable to breastfeed or choose not to breastfeed, the only food recognised by the WHO as a suitable and safe alternative to breastmilk is infant formula.
"UK regulations do not allow added sugars in standard infant formulas. The nutrient composition of infant formula sold in the UK is formulated to be similar to that of breastmilk and therefore contains naturally occurring lactose, which is not an 'added sugar'. As such, it is incorrect to suggest that UK formulas are appropriate for consideration in sugar reduction strategies."
The study, however, called for tighter regulations that controlled the amount and type of sugar in infant formula products.
"The aim of the study is not to make mothers feel guilty about their feeding choices," Bridges said.
"Instead it is to advocate for labelling transparency so parents can make informed choices and to encourage policy to consider regulation of sugar and ingredients."
The researchers proposed manufacturers should aim for formulations as close to breastmilk as possible with corresponding regulations conducted in a similar way to the taxes on sugar-sweetened drinks.
They called for mandatory disclosure of added sugar by manufacturers alongside the introduction of a clear front-of-pack labelling system. This, they said, would give consumers informed choice.
The global infant formula market is expected to increase by 9 per cent a year to £73 billion (NZ$153b) by 2025, primarily driven by an increasing working women population and the introduction of milk formulas induced with additional nutrition.
