A vaccine to prevent cervical cancer appears to work best when given to girls aged 10 to 14.

The vaccine, Cervarix, which targets the human papilloma virus which can cause cervical cancer, is being developed by GlaxoSmithKline (GSK).

Cervarix was still as effective in the 15-25 age group but the immune response was twice as high in the younger girls, the drugs giant says today.

This suggests that the effects of the jab could last longer when given at an earlier age, which would reduce the need for booster jabs. The research was to be presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington DC.

Cervarix targets two types of the virus which are responsible for about 70 per cent of all cervical cancer cases.

The researchers found that the antibody response in the 15 to 25 age group was high enough to combat the virus, matching research previously published in The Lancet.

This showed that the vaccine provided complete protection against persistent infection with papilloma virus types 16 and 18 in this group of women.

But the latest study found that the antibody response among the younger girls was double the level in the older age group.

The researchers said this finding was encouraging, and might be associated with a longer persistence of antibodies. This would be important if the vaccination were given at an earlier age.

The idea of inoculating girls against the virus is controversial because the disease is a sexually transmitted infection.

Women can catch it at any time from their first sexual contact. A large proportion are infected by the time they are 30.

But the latest research suggesting that Cervarix is more effective in younger girls will add support for early vaccination.

Dr Anne Szarewski, a clinical consultant for Cancer Research UK, said: "A vaccine that could prevent around 70 per cent of cervical cancers is an exciting prospect for all women."

Cervarix is in clinical trials involving more than 30,000 women around the world.

Around 3,000 new cases of cervical cancer - and 1,000 deaths - are reported each year in the UK.

The death rate has dropped significantly since the introduction of cervical screening, which is thought to save the lives of around 4,500 women a year.