The Food Standards Agency (FSA) said that foods are now rigorously analysed for Sudan I to IV, Para Red, Rhodamine B, Orange II, Red G, Butter Yellow and Metanil Yellow.
While these dyes can be used in industry, for example for colouring solvents, oils and waxes, they cannot be added to food.
In some well-documented cases however, inadvertent contamination of some food products has been identified.
A total of 149 local authorities across the UK carried out tests on food between December 2005 and March 2006. Sampling was carried out randomly on spices, sauces and oils at a variety of premises including ports, warehouses and retailers.
Out of 893 samples, six were found to contain illegal food dyes. Sudan I was found in one sample of tandoori masala mix from an unknown country of origin. Sudan IV was found in three samples of palm oil from Ghana, and Orange II was found in a ground red chilli product and pepper soup mix, both from Nigeria.
Where illegal dyes were identified, the FSA said that it has worked with local authorities to ensure the contaminated products were traced and that appropriate action was taken to withdraw any such products from the market. The affected materials were then disposed of in accordance with approved protocols.
Food dye contamination is a Europe-wide problem, and the EC has repeatedly warned of the danger of fraud involving several different dyes and colours.
Indeed, the Sudan dye issue has focused a great deal of attention on the food industry's ability to protect the supply chain. Since July 2003, cargoes of dried and crushed or ground chilli and curry powders coming into any EU Member State have to be accompanied by a certificate showing they have been tested and found to be free of Sudan I.
Any consignment that does not have a certificate must be detained for sampling and analysis.
Random sampling must also be undertaken both at ports and by local authorities. The FSA and local authorities randomly sample more than 1000 consignments a year of imported chilli products. All consignments found to contain Sudan I to IV must be destroyed.
Some 85 per cent of the positive findings for Para Red were done in Germany and the United Kingdom. As Germany is a key player for the import of spices in the EU it has logically notified many positive cases and is also identified as the most frequent origin of the contaminated products (when the exact origin could not be determined).
In addition to developing testing capabilities for Sudan dyes, both Germany and the UK have also developed analytical tests for Para Red.
The FSA said that Bixin a colour permitted under EC legislation for specified foods, not including spices was detected in 18 of the samples analysed. Bixin is derived from annatto seeds, which are sometimes added (ground) for their flavouring properties as an ingredient in food.
"We are currently considering the possible distinction of these two uses of bixin and annatto, as a colour and as a flavouring,"said the FSA in statement.
"The issue will be discussed with relevant stakeholders and with the European Commission."