'I'm an off-duty cop, you're under arrest'

Footage has emerged of the moment an off-duty police officer was tackled to the ground by security guards after bashing a woman in an ugly spat outside a Sydney pub.

Michael Simmons can be seen being held back in the video aired tonight by Nine News for the first time since the ordeal at the Newport Arms Hotel on Christmas Eve, 2012.

Security guards speak to Simmons and his girlfriend after glasses were thrown during an argument with the victim, Kristie Hall.

Both were kicked out and walked a few metres away when a second argument erupts, Nine News reports.

Witnesses say Simmons crash-tackled Ms Hall to get her off his girlfriend, saying: "I'm an off-duty police officer. That's it, you're under arrest."

He allegedly punched her up to four times before security guards restrained him.

A magistrate, who will sentence Simmons in a fortnight, told the officer he was entitled to defend himself and his partner but his response was excessive.

His lawyer told the court the previously highly regarded senior constable, who had been awarded a bravery medal for his work during the Victorian bushfires, faces being removed from the force and has few other job prospects, Nine News reports.