Joan Rivers' daughter is suing a doctor over her death.

Melissa Rivers, 46, is taking legal action against throat specialist Dr Gwen Korovin, who was allegedly unauthorised to practise at the Yorkville Endoscopy Clinic in Manhattan where Joan passed away after a routine endoscopy caused her to go into cardiac arrest last month.

Although the medical centre's director Dr Lawrence Cohen stepped down following the death of the star aged 88, it is believed Dr Korovin has continued working and accepting new patients at the practice.

A close friend of the Rivers family told MailOnline: ''Melissa does plan to sue the clinic. It's very difficult to discuss something so unpleasant with her, but she is going to launch a lawsuit.''

According to CNN, clinic workers claim both Dr Cohen and Dr Korovin were treating the late star in the hours leading up to her death with Dr Korovin performing an initial laryngoscopy followed by an endoscopy to help determine the cause of a sore throat and hoarseness she was suffering from.

Dr Cohen then ordered Dr Korovin to perform a second endoscopy and laryngoscopy - during which Joan's vocal chords are said to have swollen, cutting off the oxygen supply to her lungs and leading to the cardiac arrest that killed her.

Melissa claims Dr Korovin was unauthorised to practise the procedure and was only meant to observe Dr Cohen as she was not certified to practise by the clinic and therefore outside of the regulations of New York health law.

However, the upper east side clinic is denying reports that the vocal chord biopsy was performed.