A female police officer has been rushed to hospital with facial injuries after allegedly being punched in the face by a man at a Sydney police station.

A 39-year-old man has been charged after assaulting the female sergeant at Mascot Police Station late on Thursday afternoon.

WATCH THE VIDEO ABOVE: Female cop allegedly attacked by man at police station

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The man was being held in the cells after earlier being arrested in nearby Redfern on Thursday afternoon, where he’s accused of stalking a 19-year-old woman down a street, before assaulting her and attempting to perform a sexual act.

Several members of the public came to her aid with the man taking off before he was later arrested by police officers.

The 19-year-old woman suffered severe face and head injuries and was rushed to hospital.

Sydney’s Mascot Police Station. Credit: 7NEWS

The man missed the cut-off to face the bail court and was scheduled to appear on Friday morning.

A female sergeant was performing custody duties and dealing with the man when he was given access to toilet facilities, NSW Police said in a statement.

“After being returned to the cell, the man allegedly grabbed hold of the sergeant by the head and delivered five punches, alternating between his left and right fists, all connecting with the sergeant’s face,” police said.

“Other police inside the station went to the sergeant’s aid and prevented the man from escaping.”

She suffered extensive bleeding and swelling to the face. She was treated by paramedics and taken to hospital for a possible broken nose and further facial injuries.

The man was re-arrested and charged with assault police officer in execution of duty and occasion actual bodily harm, hinder or resist police officer in the execution of duty and inmate escape/attempt to escape from lawful custody.

He was refused bail to appear at Bail Division Court 7 on Friday.