We don't want to paint a picture of someone that has been incapable because of alcohol because that is not the case

Detective Sergeant Gary Flannigan

Police said the woman met a man during a night out with friends at the Subway (West End) nightclub on Lothian Road and left with him at about 0300 GMT.

She was then taken to his car, which was parked in the Castle Terrace area, and driven to a secluded spot before being raped.

Detective sergeant Gary Flannigan, who is leading the inquiry, said: "We want to hear from anyone who saw what appeared to be a drunk female, possibly being led to Castle Terrace and in to a car, but we don't want to paint a picture of someone that has been incapable because of alcohol because that is not the case.

"This was a prolonged sexual attack and the victim is naturally shocked at what has happened to her.

The woman's drink may have been spiked with GHB

"We would also like to hear from anyone who knows a man - husband, brother, boyfriend, son - fitting this description who was out on Thursday night and did not return home until after 5am on the Friday morning."

Det Sgt Flannigan added: "At this stage we are keeping an open mind on the circumstances but we have not ruled out the suggestion that the victim may have had her drink spiked."

The attacker is described as white, 25 to 30 years old, 5ft 6ins to 5ft 9ins, of stocky build, with short brown hair.

He was clean shaven with distinctive pockmarked skin around his cheeks.

Rohypnol is banned in the UK but can be obtained by prescription and is used in treatment for sleeping disorders.

GHB, which is also known as liquid ecstasy, is available over the counter and is used by some clubbers.