Olympic swimming champion Dawn Fraser says she fought off a young intruder who attacked her during a home invasion at her daughter's house at Noosaville on Queensland's Sunshine Coast.

The 72-year-old says she was awoken by intruders on Friday night and went to investigate.

Ms Fraser told Channel Seven she was startled by a teenager who threatened her and she decided to take him on.

"Out came this guy who then grabbed me around the throat and said 'I will kill you', and with that I grabbed him around the ear and hair and kneed him in the groin," she said.

"I was threatened by the way he spoke to me and I'd never been spoken to like what he called me ... I think I lost it.

"I have got a titanium knee so it must have hurt him.

"[I] came up for a holiday and here I am being threatened with my life and all our security has been taken."

Police have referred two youths to the Child Protection Unit over the incident.

Police say they are treating the investigation as a trespassing incident because no homes were broken into, nothing was stolen and no-one has made an assault complaint.