Not enough cattle in Britain are being tested for signs of BSE and therefore the true spread of mad cow disease across the country is unknown, said senior government scientist Professor Roy Anderson this week.

Compared to other European countries, Britain's testing programme is far less extensive. The majority of the 10,000 animals that have been tested in Britain have already died from the disease, or from accident, or are over 30 months old.

In France and Germany meanwhile, almost 1m cows are tested every year, a move in line with a Europe-wide testing programme, for cattle over 30 months, introduced at the beginning of this year.

Prof. Anderson, who has also worked with the government on foot-and-mouth disease policy, argued that Britain must match the Continental approach to testing in order to garner accurate information on the presence of BSE in the UK.

The Department for Environment, Food and Rural Affairs (Defra) responded to Anderson's comments with a statement that Britain is complying with EU testing legislation.

The statement admitted however that because there is no obligation on farms to implement testing programmes, many farmers were slow to come forward.