Diane Keaton has died at the age of 79.

On Saturday, editors at People reported that the Oscar-winning actress had passed away in California.

A spokesperson confirmed the sad news but declined to share any further details.

Born in Los Angeles in 1946, Diane made her debut in Woody Allen's production of Play It Again, Sam when she was 20 - with the performance garnering her a Tony Award nomination.

However, the star made her screen debut in 1970 romantic comedy, Lovers and Other Strangers, and rose to prominence two years later, when she appeared as Kay Adams in Francis Ford Coppola's epic gangster film, The Godfather.

Keaton reprised the role in the 1974 sequel The Godfather Part II and 1990's The Godfather Part III.

The actress went on to collaborate with Allen on a number of projects throughout the '70s, including Sleeper and Manhattan.

Yet, Keaton was perhaps best known for portraying the titular character in 1977's Annie Hall, the role for which she won the Academy Award for Best Actress.

In the '90s and 2000s, the artist appeared in a string of hit movies, such as 1991's Father of the Bride, 1996's The First Wives Club, and 2003's Something's Gotta Give.

More recently, Keaton featured in 2018's Book Club and its follow-up, Book Club: The Next Chapter.

She was honoured with the American Film Institute's Lifetime Achievement Award in 2017.

Keaton had a number of high-profile relationships over the years, including with Allen, Al Pacino, and Warren Beatty, but never married.

She is survived by two adopted children, daughter Dexter, 29, and son Duke, 25.