Some children's sunscreens do not offer the level of protection that they claim to, warns the Trading Standards Institute.
Children may be less protected than thought
Spot checks revealed seven out of eight sun cream products marketed at children and babies had failed to live up to their sun protection branding.
The TSI is worried parents may be unwittingly exposing their children to the risks of sun damage as a result.
It wants the government to bring in tighter regulations.
Sun creams currently have to comply with cosmetics safety laws, contained in the Cosmetics Products (Safety) Regulations 1996, which also cover general beauty products.
However, these regulations do not give guidance about what claims can or cannot be included in labelling.
Nor do they include a way for determining how well a product protects against the ultraviolet sun rays - UVA and UVB - that can damage the skin.
Sunscreens carry two values on their labels - UVA protection and a sun protection factor (SPF) relating to UVB protection.
The TSI would like to see standard tests on a sun product's SPF and UVA rating, carried out only by approved laboratories.
It is also calling for an upper limit for SPF of 30 or 30+.
An SPF of 15 is the minimum recommended by cancer experts and blocks out about 7% of UVB rays. An SPF of 30 blocks out all but 4%.
The TSI is especially concerned about UVA protection.
Ms Judith Johnson, TSI's spokeswoman on sun safety, said: "We are increasingly seeing sunscreen manufacturers focus on higher and higher levels of UVB protection, leading consumers to believe they can stay in the sun longer and so increase their exposure to the most harmful UVA rays."
Key recommendations by the TSI
Standard tests for SPF and UVA
Approved test laboratories
Upper SPF limit of 30 or 30+
Best before dates on all products
Clear use and storage instructions
School education campaigns
The TSI plans to present its recommendations to the Department of Trade and Industry and to European commissioners.
Ron Gainsford, chief executive of TSI said: "It is a major concern to us that parents could be unwittingly exposing their children to the risk of sun damage, thinking they are better protected than they actually are.
"Nobody puts sun cream on themselves or their children because it makes them look better - they do it solely for health reasons and this should be reflected in its testing regime and in the legislation governing it.
"It seems crazy that in the UK and Europe sun creams are afforded the same regulatory status as lipsticks," he said.
A spokesperson for the Department of Trade and Industry said: "We will consider supporting a voluntary code of practice to facilitate a single method of testing and clearer labelling.
"We have already discussed sunscreens at European level, and will continue to do so at the next working group meeting in Brussels in July."
Consumer group Which? has carried out its own research and found similar shortfalls.
Nikki Ratcliff, principal health researcher at Which? said: "We support the Trading Standards Institute's call for tougher regulations on sunscreens."
Which will announce its findings next week.