The Government yesterday changed its mind over the use of mobile phone hands-free kits, which were previously said to reduce radiation exposure.

New public information leaflets about mobile phone safety now say it is uncertain whether hands-free kits protect the user's head from radiation.

In August, e-commerce minister Patricia Hewitt said she was able to offer "unambiguous advice" that the kits reduced radiation levels.

That statement was based on research commissioned by the Government. But last month the Consumers' Association said its own studies indicated hands-free kits could increase the brain's exposure to radiation by up to 3.5 times.

Asked yesterday whether the Government line had changed, Chief Medical Officer for England Professor Liam Donaldson said: "Yes, it has."

Speaking at the announcement of a £7m program of mobile research, he added: "Common sense might suggest that not using a handset would reduce exposure, but tests so far have been conflicting.