Gonorrhoea is on the way to becoming an untreatable disease as strains resistant to antibiotics spread further, a European surveillance body is warning.

The disease is now the second most common sexually transmitted infection in Europe (after chlamydia) for which the UK has a screening programme.

According to the European Centre for Disease Prevention and Control, the agency that monitors spread of infectious diseases, there were more than 32,000 gonorrhoea cases in Europe during 2010.

The centre's figures show a sharp rise – from 4% to 9% – in cases of resistance to the main antibiotic used to treat gonorrhoea. In 2009 resistance was found in seven countries; last year it was found in 17.

"This indicates the risk that gonorrhoea may become an untreatable disease in the near future," said Marc Sprenger, director of the centre.

The Health Protection Agency has already warned about the spread of gonorrhoea in England among young people. There were more than 20,000 cases in England in 2011, a 25% rise on the previous year when there were 16,835 cases.

The UK collects more complete data on the disease than most countries since reporting is mandatory, so the numbers from the European centre represent a considerable under-estimate of the true picture.

More than half of all new gonorrhoea infections in England were in the under-25s and there was a sharp increase in girls aged 15 to 18.

Gwenda Hughes, head of STI surveillance at the HPA, warned that resistance was a global issue. "This bug has successfully managed to develop resistance to every treatment used for it for a decade. We are running out of options for managing this infection. We are concerned in the future it will become very difficult to treat."