Leading brands of suncream fail to live up to their claim to protect against sunburn, a Which? magazine report says today.

Boots Soltan, Superdrug and Simple products did not provide the degree of protection claimed on their labels when the Consumers' Association conducted rigorous tests.

It tested 10 creams which claimed a sun protection factor of 15 or 16, and five suncream sprays for children that claimed an SPF of 30.

It found that Simple, Boots Soltan and Superdrug products labelled as SPF 15 had SPFs of 9, 10, and 11 respectively.

Officially, suncreams are allowed to be 20% either side of the claimed SPF, since tests results can vary according to skin type. So a product that claims to provide an SPF of 15, is allowed to fall within the range of 12 to 18.

But these three products did not even meet the industry's own standards.

The higher the SPF, the more a product should protect from UVB rays, which cause 80 to 90% of skin damage.

All the other suncreams tested met the industry standard, but not all provided the degree of protection promised on the label. Delph cream had an SPF of 12, and Hawaiian Tropic was 13.

Superdrug's children's cream and Sainsbury's Blue Parrot lotion claimed an SPF of 30, but scored 27 and 28 respectively in Which? tests.

Many products also offer protection from UVA rays, which can also contribute to cancer and ageing. The UVA star rating system developed by Boots has been widely adopted, more stars meaning better protection up to a maximum of five.

Which? tested the products with the highest ratings from each brand. Again, some did not live up to their claims. Nivea children's sunspray offered significantly less protection than its three-star rating promised.

Superdrug children's and Simple suncreeens fell just short of the level required for four stars. Only the suncream from Boots lived up to maximum five-star protection.

Each year 69,000 cases of skin cancer are diagnosed in Britain, and there are more than 2,000 deaths. The rates have risen dramatically since 1995 as more and more people take holidays abroad.

The companies that failed the Which? tests said their products had passed their own tests using the same methods. The Which? editor, Malcolm Coles, said the industry needed to develop more robust testing methods.

He called for labels to reflect the lower end of a product's SPF range, so that consumers could know exactly what they were buying.