A Colombian teenager has been arrested over a series of sexual assaults around the CBD that had prompted a warning from detectives for women to not go out alone.

The 17-year-old Colombian national was found at a camping ground in Johanna, near Apollo Bay, and arrested soon after noon on Friday.

He was in custody being interviewed by police on Friday, but had not been charged.

The arrest comes days after sexual crime squad detectives made a public appeal for help to catch a sexual predator they believed was stalking young women in Melbourne’s CBD.

In the most recent attack, a 22-year-old woman was assaulted in a building stairwell early on Saturday morning after being dragged from Southern Cross Station.