Cessnock mineworker Kenneth Harris has accused Austar Coal Mine Pty Ltd of secretly filming him and his colleagues without authority in an office at the Pelton Coal Handling and Preparation Plant on Wollombi Road, Pelton, in March, a court attendance notice stated.

Counsel for the company, Shane Prince, entered a plea of not guilty in Newcastle Local Court on Friday.

Mr Prince told magistrate Elaine Truscott the company had a defence, but declined to say what that defence was.

The case was adjourned until November.

The company is accused of concealing a camera inside a lever arch folder.

The camera was switched on while the folder was left in an office between March 11 and 15 this year and the company did not have authority to carry out surveillance, court documents stated.

It stated employees were given no warning the camera would be monitoring them and there was no signage to alert people who entered the office that they would be under surveillance.