US actress Joy Harmon, who was best known for a provocative short scene in the classic film Cool Hand Luke, has died aged 87.

Harmon died at home in Los Angeles on Tuesday after being ill with pneumonia for weeks, US media reported.

Her character did not have a line in the Paul Newman prison drama and was only on screen for about three minutes, in a car-washing scene rife with sexual innuendo.

In her brief but famous scene, Harmon washes a car and squeezes soap from a sponge on her body, drawing the attention and remarks of prisoners who watch as they dig a ditch.

Although officially credited as The Girl, her character was called "Lucille" by one of the prisoners distracted by her car washing.

It became the best known moment of her career, which spanned 32 credited appearances in movies and TV from the 1950s to the early 1970s, according to IMDB.

"I was just washing a car to the best of my ability and having fun with it, with the sponge and everything," Harmon told Entertainment Weekly in 2017.

"My concept of the [scene] was not like what came out. I was not aware that there were two meanings to things that I was doing, and I'm still not really that much aware of what they all were."

Harmon started in the entertainment business as a child model and pageant queen and worked her way up through appearances on comedy and quiz shows.

Most of her movie roles were through the 1960s and she also appeared in series including Bewitched, Batman, The Man from U.N.C.L.E, The Beverley Hillbillies, The Odd Couple and The Monkees.

After acting she worked at Disney Studios and in 2003 she opened a bakery in Los Angeles but still got fan mail sent to her every week, US media reports.

Harmon is survived by three children and nine grandchildren.