Eight out of 10 people believe that they do not know enough about the long-term health effects of genetically modified food to allow the commercialisation of GM crops.

Their concerns are made clear in the findings of a poll that adopted the Government's own GM debate questionnaire.

The survey, conducted by the Internet Marketing Research Services, an internet polling organisation, used a sample of 2,400 people. Its results are likely to reproduce closely what the Government's own pollsters will report in September, just before a decision is taken whether to give the go-ahead to GM crops.

The strongest response was that 83 per cent of the public said they did not think people knew enough about the long-term effects of GM food on our health.

The public also showed intense scepticism about the motives of GM companies. Seventy-eight per cent of those polled said they were "worried that this new technology was being driven more by profit than by public interest".

Similarly, 67 per cent thought that GM crops would benefit mainly the producers and not ordinary people.

Three quarters of those polled said they were worried that if GM crops were introduced it would be very difficult to ensure that other crops were GM-free. Fractionally fewer, 71 per cent, were concerned about the potential negative impact of GM crops on the environment.

Opinion became more fragmented when it came to how it might benefit developing countries; 48 per cent believed that GM crops could benefit them, with 34 per cent disagreeing.