Documentary filmmaker and cinema verite pioneer Robert Drew has died, aged 90.

The veteran director passed away at his home in Sharon, Connecticut on Wednesday morning (30Jul14).

While the cause of his death has yet to be revealed, his son Thatcher Drew says in a statement that his dad "had been declining for some time and it was not completely unexpected".

Drew began his career as a correspondent and editor for Life Magazine and also served as a pilot during World War Ii. His combined experiences helped him develop his signature style of cinema verite filmmaking, a genre which features observational filming in order to capture reality, which has since become a staple in documentary filmmaking.

After founding his film company Drew Associates in the early 1960s, he created more than 100 films on social issues, politics and the arts, and is considered the "father" of cinema verite.

Drew also developed lightweight cameras, and his popular film Primary, which followed U.S. President John F. Kennedy and opponent Hubert Humphrey during the 1960 Wisconsin presidential primary, was the first film to ever use a sync-sound motion picture camera.

Over his five-decade career, he also directed such films as The Chair, Faces of November, From Two Men and a War, and Man Who Dances, for which he won an Emmy in 1968.

In addition to his numerous awards from various organisations and film festivals, six of Drew's films are archived at the Academy of Motion Picture Arts and Sciences, and two are in the National Film Registry of the Library of Congress.

He is survived by three children and three grandchildren. His wife Anne, who frequently collaborated with him for his films, passed away in 2012.