A woman has been discovered in the boot of her own car after allegedly being abducted and sexually assaulted by a group of men in Melbourne's south-east.

Sexual crimes squad detectives have been told the woman was approached by a number of men and put into the boot while at a Bourke Road shopping centre car park in Clarinda about 1.30pm on Tuesday.

The ordeal lasted more than two hours. Police found the woman, still in the boot, at the intersection of Vernal Road and Leham Avenue in Oakleigh South at 4pm.

Early on Wednesday morning, police were not able to say if the woman knew the men, how many men were involved, or provide a description of the alleged offenders.

The woman has been taken to Monash hospital for medical treatment. Detectives are investigating the incident and urge anyone with information to contact Crime Stoppers on 1800 333 000.

The investigation is ongoing.