Illegal and potentially cancer-causing food dyes have been found in sweets on sale in Bradford and across West Yorkshire.

A major customer alert has now been issued over the fluorescent versions of traditional Asian sweets, which are said to particularly appeal to children.

West Yorkshire Trading Standards said sweets containing the illegal fluorescent pink or yellow dyes Rhodamine B and Auramine had so far been found in Bradford and Kirklees, but could be being sold elsewhere.

The problem was picked up through a testing programme, where samples of Asian sweets had been taken from a number of outlets across West Yorkshire and tested by the West Yorkshire Public Analyst.

Criminal investigations have now begun but a trading standards spokesman said it appeared that the contaminated sweets were not all coming from a single supplier and as a result not all the sources had yet been identified.

Consumers and businesses are therefore being asked to be vigilant and report any sweets which glow under ultraviolet light to trading standards through the Citizens’ Advice Consumer Helpline on 08454 040506.

Rhodamine B appears green in powder form but when added to water turns a vivid fluorescent pink.

It is not a permitted food colour and is considered to be potentially carcinogenic. It is commonly used to stain slides in laboratories and in the sewage industry to test for leaks in drains.

Auramine appears yellow or orange in both powder and liquid forms. It is also commonly used to stain laboratory slides. It is not a permitted food colour and is also potentially carcinogenic.

A trading standards spokesman said both illegal dyes would fluoresce under ultraviolet light, which could help food outlets and customers identify them.

Yesterday, businesses selling traditional Asian sweets were being urged to contact their suppliers to ask whether the illegal dyes were present in products.

If they were an ingredient, the sweets should be removed from sale immediately, the spokesman said.

Councillor Val Slater, chairman of the West Yorkshire Trading Standards committee and a Bradford councillor, said: “These brightly-coloured sweets, made from milk and sugar, are especially attractive to children therefore, in order to protect their health, it is important they are removed from sale.

“Anyone who has a legitimate concern relating to these items, should contact the helpline.”