Veteran American entertainer Jerry Lewis, whose goofy brand of physical comedy endeared him to millions in a career spanning six decades, died on Sunday aged 91, his agent told AFP.

One of the most popular comic actors of the 1950s and '60s, Lewis perfected the role of the quirky clown in slapstick comedies like "The Nutty Professor" but also won acclaim as a writer, actor and philanthropist.

"Very sadly Jerry Lewis has passed," his agent Jeff Wijtas told AFP.

Variety reported that the comic legend died in Las Vegas early Sunday morning.

Honoured with accolades at home and abroad, including a nomination for the Nobel Peace Prize in 1977, Lewis became known as much for his tireless efforts to promote awareness of Muscular Dystrophy as for his unique brand of physical comedy.

Over the course of 45 years, he raised some $2.45 billion for combating the disease with an annual television event.

Born Joseph Levitch in Newark, New Jersey to two New York City entertainers, Lewis first took centre stage at the tender age of five, when he performed "Brother, Can You Spare a Dime?"

He began playing at resorts outside New York City that catered to Jewish patrons, known by touring entertainers as the Borscht Circuit.

By age 15, he had assembled his own routine of comedic lip-synching and made the rounds of New York talent agents, although only a burlesque house in Buffalo was interested.

At the age of 20, however, everything changed for Lewis, when he embarked on arguably one of the most successful entertainment partnerships of all time with smooth crooner Dean Martin.

The two fed off each other in now-classic comedy gags, including pratfalls, slapstick and lots of seltzer water.

They signed a long-term contract with Paramount Pictures, and starred in 1949's "My Friend Irma", where Lewis delivered a performance described as "the funniest thing in the picture".

'Finish what I started'

Other notable films in Lewis' repertoire include "It's a Mad, Mad, Mad, Mad World" (1959), "The Geisha Boy" (1958) and "Funnybones" (1984).

His box office grosses, spanning nearly 50 years, total $800 million ─ an impressive figure since movie tickets cost no more than 50 cents during the height of his popularity.

After 17 films together, the Lewis-Martin partnership split in 1956, but Lewis continued his career in comedy and Hollywood.

He won acclaim for his dramatic role in the 1983 Martin Scorsese film "The King of Comedy", co-starring with Robert De Niro that showed his acting versatility.

In recent decades, Lewis had been plagued by health problems, and was declared clinically dead in 1982 after a heart attack.

Ten years later he was diagnosed with prostate cancer and in 1997 found out he had diabetes.

A diagnosis of spinal meningitis in 2000 further caused his health to deteriorate.

But he was determined not to let ill health keep him from working as long as possible, including on a Broadway musical adaptation of "The Nutty Professor" as recently as 2011.

"I have to finish what I've started," he told the Los Angeles Times in a 2010 interview. "I want to do it before I leave."