Opposition Leader Bill Shorten has identified himself as the senior Labor Party figure who had been the subject of rape allegations dating back to the 1980s and says the matter is now "over".

He has strenuously denied the claim.

Victorian Police had been investigating the matter but confirmed on Thursday that they will not be proceeding with criminal charges.

At a press conference the Labor leader addressed the allegation, which was published on his female accuser's Facebook page several months ago.

"Late last year I learned that a claim had been made about me, going back to when I was 19," Mr Shorten said.

"I will not go into the details, except to say that the allegation was untrue and abhorrent.

"The allegation was made by someone that I knew briefly at that time. There is absolutely no basis to the claim."

Mr Shorten said he cooperated with a police investigation "to clear my name".

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"The police have now concluded the investigation. The decision speaks for itself. It is over," he said.

Earlier Victoria Police said it would not proceed with charges.

"Investigating police sought advice from the Office of Public Prosecutions, which advised there was no reasonable prospect of conviction," a statement from Victoria Police said.

"All parties have been notified that Victoria Police will not be proceeding with criminal charges."

The alleged victim, who posted the claims on a Facebook page late last year, said that the sexual assault took place at a Young Labor camp near Geelong in the 1980s.

The ABC has contacted the woman involved but has not had a response to questions.