Police have received information about a potential witness over an alleged sexual assault at a New Year's Eve dance party nearly twenty years ago.

They were looking for a man named Barney, but based on a phone call they have received, they no longer need anyone to come forward with any information.

Police say the complaint about a Christchurch woman being sexually assaulted at a dance party in the Nelson area, called Entrain, on New Year’s Eve 1995, was made recently.