THE Duke of Rothesay has praised American comedian Joan Rivers for her "enormous zest for life" after she died aged 81.

Rivers was admitted to hospital last week after suffering a heart attack in a doctor's surgery. Her daughter Melissa announced her death on Thursday "with great sadness".

The Duke and Duchess of Rothesay were said to be "deeply saddened" by the death of Rivers, who attended their wedding in 2005.

She also performed for Charles, Prince William and Prince Harry at the We Are Most Amused comedy gala, in aid of the Prince's Trust, for Charles's 60th birthday.

Charles said: "She will be hugely missed and utterly irreplaceable."

Rivers had one grandson, Cooper. Her husband, Edgar Rosenberg, died in 1987.

Her funeral will be invitation-only on Sunday at Temple Emanu-El, a landmark synagogue on New York's Fifth Avenue.

The New York Medical Examiner's Office said the cause and manner of death are pending further studies.

The city's Governor Andrew Cuomo described Rivers as an iconic New Yorker whose wit will always be remembered. "Joan made the nation laugh for more than 50 years, and for that we will always be grateful," he said in a statement.