An innovative scheme to trace the partners of gay men diagnosed with HIV is to be launched in Britain in the new year. Its aim is to cut the number of men who remain ignorant that they have been infected, putting others at risk and delaying the start of treatment.

Latest figures from the Health Protection Agency show that while the number of people newly diagnosed with HIV is falling, the proportion unaware they have been infected has remained unchanged.

Clinics for sexually transmitted diseases have run partner notification schemes since the 1970s. But their methods are "archaic, outdated and difficult for the clinics to apply," says Carl Brunell, chief executive of GMFA (originally Gay Men Fighting Aids), which has developed the new scheme.

"If you have a sexually transmitted infection it vastly increases your risk of being infected with HIV or of passing it on. Not everyone knows they are infected because the early symptoms of HIV can often be passed off as flu. But if someone has been diagnosed with HIV it had to come from somewhere. Long gone are the days when people could wonder if they got it from a toilet seat."

Existing schemes require patients diagnosed with an STD to contact their sexual partners to tell them. "It is the worst second date ever. People don't want to do it. There is an obvious embarrassment factor," says Mr Brunell.

Dating has also changed. Around 60 per cent of gay men meet their partners through gay dating websites. The new scheme , designed by GMFA, will enable patients diagnosed with HIV to log into the websites and upload their details, sending messages to the in-boxes of their partners, alerting them that they may need to contact the clinic directly for an HIV test – without identifying themselves.

The system is password protected and only accessible for a limited time by patients diagnosed in the clinic. It will be launched in eight pilot sites next year before being extended.

"We spent six months talking to the clinics and the gay dating services, discussing what they needed, and what systems gay men used in order to ensure we didn't scare the horses," Mr Brunell said. "We are starting with gay men first but if it is successful we will see if it can be extended to include heterosexuals."