Girl, 14, found on street drunk and half-naked

Tests are now being carried out to determine whether the teenager had been raped or sexually assaulted.

The girl was so drunk she has no recollection of what happened to her or how she came to lose her trousers and underwear.

Police are also investigating whether she had spent time at an under-18s nightclub, events which are growing in popularity despite reports of widespread drinking and drug-taking.

Although alcohol is banned, there are concerns about the number of youngsters smuggling drink inside and drinking before and after the events.

A police source said: "The girl was found wandering along one of the back streets in Edinburgh.

"She had drunk so much alcohol she was absolutely inebriated. She had lost her trousers and her knickers and didn’t know what had happened to her or why she had taken them off. She was taken to Gayfield police station and sent for tests to see whether she had been sexually assaulted.

"Because she was so drunk she had no recollection of what had happened to her that evening or what she had been doing or who she had met."

Unless witnesses come forward, detectives may never determine what happened to the teenager.

Tam Hendry, from the charity Streetwork, which works with youngsters, said: "This is a truly shocking incident and for some time now we’ve been worried that something like this could happen. There is an urgent need to put more youth workers out on the street so that situations like these don’t arise."

Up to 2,000 youngsters flock every weekend to early-evening under-age discos in Edinburgh. Because the nightclubs that host the events are already licensed they do not need any special checks by councils.

A spokeswoman for Edinburgh Council said it would examine the facts of the case to see whether any action needed to be taken.