Decades-old audio tapes of former U.S. first lady Jacqueline Kennedy are providing a rare glimpse of her life, opinions and marriage to the young president John F. Kennedy.

The hours-long interviews on the tapes were recorded months after the 1963 assassination of her husband. She talks candidly, saying the time she and her husband were in the White House were their “happiest years.”

The tapes reveal her opinions on former heads of state and other prominent figures. The former first lady called then-French president Charles de Gaulle an “egomaniac,” the civil rights icon Reverend Martin Luther King Jr. a “phony,” and future Indian prime minister Indira Gandhi a “bitter, kind of pushy, horrible woman.”

She also opens up about President Kennedy's opinions about his vice president, Lyndon Johnson. She says the president would ask her “Can you ever imagine what would happen to the country if Lyndon were president?” Mr. Johnson took office following President Kennedy's assassination.

She does not discuss the president's death, but mentions that he joked about being assassinated following the Cuban Missile Crisis in 1962.

As a young widow, Kennedy agreed to be interviewed by White House aide Arthur Schlesinger Jr. on the condition the tapes would not be released until long after her death. She died in 1994.

The Kennedys' daughter, Caroline, decided earlier this year to release the tapes in coordination with the 50th anniversary of her father's presidency.

The eight-and-a-half hours of oral history also are being released in the book Jacqueline Kennedy: Historic Conversations on Life With John F. Kennedy.