The debate over fluoride in water is likely to be resurrected this week with Government support for the measure.

Health Secretary Alan Johnson is to offer help to health authorities who want the chemical put in local supplies.

The move is part of Gordon Brown’s commitment to ensure the NHS focuses on prevention as well as cure.

It is claimed fluoridation can lead to significant reductions in tooth decay in children and adults.

However, campaigners against it say it is “mass medication” and an infringement of civil liberties.

Others claim over-exposure to fluoride can cause damage to teeth by marking the enamel.

Mr Johnson says a full public consultation will take place before any plans are put in place but opponents have accused the Government of using “leading questions” in opinion polls to inflate support.

Mr Johnson claims fluoridation could help to address health inequalities – giving children from poorer backgrounds a dental health boost that could last a lifetime.

In Birmingham, fluoride has been added to tap water for more than 40 years. Children there have half the level of tooth decay than those in non-fluoridated Manchester.

By law, water companies must fluoridate drinking water supplies if asked to do so by a strategic health authority.