ABI the industry trade body, has agreed to extend the ban to reassure people worried about taking a predictive test in case insurers use an adverse result against them. The moratorium was due to run out in 2011.

Stephen Haddrill, the ABI's director general, said: “The moratorium means people can insure themselves and their families, even if they have had an adverse result from a predictive genetic test.”

ABI hopes that the extension will help to quell concerns that the tests will create a “genetic underclass” of uninsurable individuals. Experts were worried that people would avoid taking tests that were vital to their health out of fear that they would subsequently be unable to buy insurance.

Under the moratorium, first agreed with the government in 2001, insurers cannot ask customers whether they have had genetic testing unless they want to buy a life insurance policy worth more than £500,000. The ban also covers critical illness policies worth up to £300,000 and income protection insurance paying annual benefits of up to £30,000.

Before selling a policy worth more than these limits insurers are permitted to ask for the results of genetic tests that have been approved by the Government's Genetics and Insurance Committee.