A woman has been arrested and charged after an incident in which she reportedly assaulted a man with a hammer while he was in a hospital bed in Sydney.

Emergency services responded to a call at Royal Prince Alfred Hospital in Camperdown around 12:15 AM on Thursday concerning an alleged attack.

According to New South Wales Police, 46-year-old Viki Graham is accused of entering the hospital and striking a 63-year-old man, who was acquainted with her, on the head with a hammer.

The victim sustained severe injuries and is currently in critical condition.

Ms. Graham was apprehended at the location and subsequently taken to Newtown Police Station, where she was formally charged with wounding with intent to cause grievous bodily harm.

She has been denied bail and is scheduled to appear in a bail court on Thursday.

NSW Health has been approached for a statement regarding the incident.