Lawyers say Joan Rivers's daughter Melissa Rivers is "outraged" by findings that errors were made at a New York City clinic where the comedian suffered a fatal complication during a medical procedure in September.

"Ms. Rivers is outraged by the misconduct and mismanagement now shown to have occurred before, during and after the procedure," a spokesperson said in a statement to the U.S.-based celebrity information show ET.

Melissa Rivers also indicated that she'd work to ensure the safety of future patients.

In a report Monday, state investigators revealed that the Manhattan clinic that treated Joan Rivers before her death made several errors, including failing to keep proper medication records and snapping cellphone photos of her while she was unconscious.

Rivers, who was 81, died Sept. 4. New York City's medical examiner found she died of brain damage due to lack of oxygen after she stopped breathing during an endoscopy days earlier.

Death a 'therapeutic complication'

A report released by the state Department of Health on Monday cited Yorkville Endoscopy for numerous deficiencies related to the Rivers case, although negligence is not alleged. The comedian's death was classified as a therapeutic complication.

As a result of the state investigation, the federal Department of Health and Human Services has given Yorkville Endoscopy until Jan. 7 to correct deficiencies to avoid losing accreditation for the government's Medicare program covering the elderly.

In a statement to NBC News on Monday, Yorkville said it has submitted a plan to state and federal accreditation agencies addressing all the issues raised. It said the physicians referenced in the report no longer provide services there.

Staff took cellphone photos

The state report said the Manhattan clinic "failed to identify deteriorating vital signs and provide timely intervention" in Rivers' case.

Investigators found conflicting information in Rivers' medical records regarding the amount of the sedation drug Propofol she was administered and about the time resuscitation was initiated. They also faulted the clinic for allowing a surgeon who was not a member of the medical staff to perform two nose and throat scoping procedures.

Investigators also noted that a staff member took cellphone photos of Rivers and a surgeon while she was under anaesthesia without her consent and in violation of the facility's cellphone policy.

With files from CBC News