By Matthew Hill BBC Health Correspondent

Hospital specialists are warning of an epidemic in sexually transmitted diseases because of chronic under funding of their clinics across the UK.

The BBC has obtained figures for some parts of the UK which reveal a doubling in the time it takes to get an appointment for tests.

The longer somebody has a sexually transmitted infection, the worse the consequences are going to be

Dr Colm O'Mahony

The government has earmarked �47m to fight sexually transmitted disease.

But experts will on Tuesday tell ministers their specialism needs an instant injection of �200m if it is going to stem the rise in these destructive diseases.

They are particularly worried about a rise in cases of the infection chlamydia.

It is estimated that nearly half of men and women have had the bacteria by the time they are 40, and cases have more than doubled over the past five years.

No children

Jane Griffiths is campaigning to raise awareness

The infection can be cured, but if untreated it can cause infertility. Many cases go unnoticed because symptoms are not always easy to identify.

It is thought that it has already cost thousands of couples the chance to have children.

Chlamydia infection increases the chance of an ectopic pregnancy. This is when the embryo starts to grow outside the womb, and poses a life-threatening risk to mother and baby.

Labour MP Jane Griffiths is campaigning for action. Years ago she lost her baby through an ectopic pregnancy, although not because of chlamydia infection.

She said: "You lose a child, but you almost lose your own life as well.

"Hundreds and hundreds of women go through the same thing every year."

The situation is not helped when clinics for sexually transmitted diseases cannot cope with the sheer numbers of patients.

Understaffing

Dr Colm O'Mahony has to turn patients away

Dr Colm O'Mahony is the only consultant in the Chester unit and serves a population of 300,000.

He should have two more consultants working with him but there isn't enough money to fund the posts.

Dr O'Mahony told the BBC his case was by no means unusual, and that most other clinics were severely understaffed.

Lack of help meant he was having to turn away patients who come to what are supposed to be open access clinics.

"The longer somebody has a sexually transmitted infection, the worse the consequences are going to be, both in terms of long term damage, and the risk that they are going to spread it further."

Figures obtained by the BBC for the North West region alone show patients are now waiting around a month to get an appointment.

That is twice as long in most clinics as it was six months ago.

The Aids charity the Terrence Higgins Trust echoed concerns about the state of the UK's sexual health and HIV services.

Nick Partridge, chief executive, said: "Evidence suggests that the longer a patient has to wait for an appointment at an STI (sexually transmitted infection) clinic, the less likely they are to show up.

"A recent report showed that more than 40% of patients are waiting more than a week to be seen, and one in ten are waiting more than a fortnight.

"We now have the highest rate of STIs since the founding of the NHS, clearly indicating that easy access to good sexual health services is more important than ever."