A court has heard CCTV failed to capture the moment the son of New South Wales MP Philip Donato allegedly assaulted police officers at Bathurst in the state's central west.

Peter Christopher Donato has pleaded not guilty after being charged with attacking the officers outside the Oxford Hotel in April 2019.

The alleged assault occurred after Mr Donato and his friends were denied entry to the pub because police believed they were intoxicated.

Senior Constable Kyle Bugden gave evidence about the moments leading up to the incident.

Senior Constable Kyle Bugden (left) gave evidence in Bathurst Local Court. ( ABC Central West: Joanna Woodburn )

The Bathurst Local Court has heard the hotel's CCTV did not record two minutes just before 10 o'clock that night, which is the time that the alleged assault occurred.

In cross examination, Senior Constable Bugden agreed with the defence counsel, Mason Manwaring, that it was "remarkable" that the security camera failed at that "critical" time, but told the court the hotel's CCTV had previously been faulty.

Senior Constable Bugden was also questioned about whether Mr Donato threw punches and whether they hit his colleague, Senior Constable Burden.

Senior Constable Bugden replied "Yeah, I believe they did".

Senior Constable Bugden told the court he believed Senior Constable Burden fell to the ground as a result of "physical contact" with Mr Donato.

"I don't know whether it was the result of punches or physical grabbing," Senior Constable Bugden told the court.

The trial continues.