Senior NSW cop denies assault

A suburban NSW police chief will fight allegations he assaulted another man, believed to be a fellow police officer.

Parramatta Inspector Mathew Edward Lonergan, 53, faced Sydney's Downing Centre Local Court on Thursday on a single charge of assault.

"In this matter I'm instructed to enter a plea of not guilty to the one sequence," his lawyer said.

Court papers name the alleged victim as Todd Edward Kirk, who was allegedly assaulted between December 2013 and March last year at Parramatta.

Charges were only laid in September, following an internal NSW Police investigation.

A NSW Police spokesman was unable to confirm if the alleged victim in the case was a serving officer.

It is understood Parramatta-based Leading Senior Constable Todd Kirk is currently attached to another western Sydney police station but AAP was unable to reach him on Thursday.

Lonergan has been suspended with pay and did not answer questions outside court.

The matter will return to court later this month.