The findings, by the Ministry of Agriculture, Fisheries and Food and the Department of Health, found low levels of dioxins and PCBs - believed to cause cancer and have "gender-bending" effects - in all the samples of different brands of fish fingers bought in supermarkets.
The research revealed greater levels of the pollutants in fresh fish sold for the table, with the highest in oily fish, such as herring, which the Government has been urging people to eat for health reasons.
Environmental Data Services, the respected pollution information firm which has reviewed the findings, says they show that adults would be "unwise to eat oily fish" more than once a week and that "children should be even more careful to limit their fish consumption".
But no warning was issued when the research - the first of its kind ever carried out by MAFF - was published in August. Not even a press release was put out. Indeed the report was so buried among technical documents on the internet that even a MAFF spokesman had difficulty in finding it last week.
News of the report will embarrass Ministers and increase alarm about the state of Britain's food following last week's revelations about high levels of pesticides in vegetables, recent warnings about antibiotics in meat, and long-running concerns about genetically modified produce.
The revelations are particularly shocking because fish has long been promoted as a healthy, natural food. For years official bodies have been telling Britons to eat more oily fish to protect against heart disease.
Dioxins - created during chemicals manufacture - and PCBs - once widespread in electrical equipment - are two of the world's most dreaded pollutants. Both are believed to cause cancer, to damage the nervous and immune system, and to have "gender bender" effects which cut sperm counts, reduce fertility, disrupt hormones and cause genital malformation.
The World Health Organisation (WHO) has warned that "subtle effects may already be occurring in the general population" even at routine levels of exposure. Figures given in the report - entitled Food Surveillance Information Sheet No.184 - suggest that children already take in levels of the poisons from food and the environment that exceed the WHO upper limits, putting them at particular risk from the polluted fish.
Adults are less vulnerable because they are bigger.Reuse content