Distraught friends of Britt Lapthorne, a 21-year-old RMIT student, have launched a plea for information.

A Facebook search page set up by the backpacker's friends, said Ms Lapthorne was last seen at a nightclub in Dubrovnik.

Her father, Dale Lapthorne of Eden Park on Melbourne's northern outskirts, confirmed that his daughter was missing.

"It is a fact but all I can ask you to do is contact the AFP (Australian Federal Police) or DFAT (Department of Foreign Affairs and Trade,'' he said. "I've been advised by DFAT that we really don't want to sensationalise this story and I certainly don't want it sensationalised.''

Croatian police confirmed they had received a report about Ms Lapthorne and said they had been searching for her since it was lodged.

A police officer in Dubrovnik said Ms Lapthorne had been with a group of friends at a nightclub when she disappeared. So far, however, police there have no leads.

Ms Lapthorne's Facebook profile lists her interests as travelling, reading and movies.

A photo gallery entitled 'Sarajevo', featuring images of Ms Lapthorne with fellow backpackers, was posted on her Facebook profile on September 15, three days before her disappearance.

Ms Lapthorne's mother, Elke, posted a message on the Facebook site created by her daughter's friends, asking those had who met her daughter or had information to email DFAT.

"If anybody has interesting/relevant information (it may not appear relevant to you but to the authority it could be) please forward to DFAT,'' she wrote.

The acting principal of the Kilmore International School, Rod Mumford, said Ms Lapthorne was a former student who graduated with her International Baccalaureate Diploma.

"I remember her, I think it was three years ago she was here,'' he said. "I didn't actually teach her so I don't know her very well but she was just a normal, everyday kind of girl.

"This is the first that I've heard about it I might just ring her parents this afternoon.''

The creator of the Facebook 'missing person' page, Tara, said Britt was last been seen in Dubrovnik a week ago.

"I started this group because anything is possible and there is always hope. ANYONE who is out there travelling in Croatia or Bosnia who met Britt or may know of her whereabouts PLEASE contact her mother (or me and I will pass the message on).

"I only knew her for a few weeks but they were the best weeks of my life!"