The 48 hour access target for all sexual health clinics will be impossible to meet on the basis of current evidence, claims an editorial in the journal Sexually Transmitted Infections.
The target is scheduled to take effect in 2008, and was prioritised last week in the NHS Operating Plan for 2006/7, which sets out the business and financial arrangements for the next two years.
The authors, STI co-editor Dr Helen Ward, and immediate past president of the British Association of Sexual Health, Dr Angela Robinson, warn that "failure to deliver on this infection control measure will cost the public purse dearly in the long run."
Boosting the efficiency of services, which many clinics have already done to cope with rising demand over the past decade, will simply not be enough, they write.
They acknowledge the government's commitment to improving sexual health service provision, outlined in its public health white paper, Choosing Health, published in November 2004
But cash strapped trusts are simply not ploughing enough money into sexual health, they say.
"The government has earmarked money for investment in services, but it is becoming clear that a considerable proportion of this will not reach sexual health [clinics] as many primary care trusts struggle with deficits and other priorities."
They cite examples of numerous surveys, pointing to continued long waits for access to routine appointments - as high as 28 days in Northern Ireland - and the increasing trend for restricted access.
Almost one in five clinics has introduced a system whereby patients can only ring to enquire about appointment slots up to two days in advance, rather than being given an appointment within the next two days, according to a survey carried out by the BBC programme Panorama in October.
Only 7 per cent of clinics were able to offer a routine appointment within 48 hours, the same survey found.
A forthcoming survey of sexual health leads in primary care trusts and specialist clinicians, due to be published in the next few weeks, is expected to reveal a similarly gloomy picture.
"There is clearly a continued crisis in GUM services in the UK," write the authors. " to neglect this area will not just mean patients inconvenienced by long waits increased waiting will lead to increased transmission of STI, and potentially of HIV infection."
They add: "Improving access to STI diagnosis and treatment services must be a public health priority at all levels."