Scientists believe they have discovered a vaccine that can protect against gonorrhoea for the first time.

Researchers in New Zealand looked at the use of the meningitis vaccine MeNZB on people aged 15-30 and found gonorrhoea cases had fallen by 31% among the group.

The sexually transmitted infection was previously proven to be resistant to medicine.

The study, published in the Lancet, said exposure to MeNZB was "the first time a vaccine has shown any protection against gonorrhoea".

The report said: "Gonorrhoea is a major global public health problem that is exacerbated by drug resistance.

"Effective vaccine development has been unsuccessful, but surveillance data suggest that outer membrane vesicle meningococcal group B vaccines affect the incidence of gonorrhoea.

"These results provide a proof of principle that can inform prospective vaccine development not only for gonorrhoea but also for meningococcal vaccines."

At least three people in France, Japan and Spain have an untreatable strain of the infection, the World Health Organisation has warned.

Gonorrhoea affects an estimated 78 million people each year.

Although gonorrhoea is one of the most common sexually transmitted diseases in the UK, people who have it may be unaware because it does not always display any obvious symptoms for many months.

The infection disproportionately affects women and can lead to pelvic inflammatory disease, ectopic pregnancy and infertility, as well as increasing the risk of HIV.