London: Teenagers as young as 13 are being offered a smartphone app that allows them to track down free condoms.

The iPhone app works using satellite positioning to plot a user's location on a map.

It then provides directions to the nearest health clinic, pharmacy or youth club where teenagers can pick up "emergency contraception" and seek treatment for sexually transmitted infections.

Since its launch earlier this month, 85 teenagers have downloaded the free app, which has been dismissed by critics as "a joke".

There are no restrictions on who can download it, but to use it to get free condoms, users have to be aged between 13 and 19 and registered with a national sexual health programme called the Kent C Card Scheme.

But Tory MP Nadine Dorries, a campaigner for teenage sexual abstinence, said: "It sounds like a real gimmick and I just can't see the teenagers who most need this kind of service actually using it."