French composer Francis Lai, who won an Oscar for “Love Story” and penned the beguiling theme for “A Man and a Woman,” has died at the age of 86, the mayor of Nice announced on Wednesday. No cause of death was reported.

Lai’s plaintive piano melody for “Love Story,” the 1970 tearjerker that made stars of Ryan O’Neal and Ali MacGraw, was his biggest hit, earning him an Oscar and a Golden Globe. His soundtrack recording was all over radio in early 1971, reaching no. 37 as a single and no. 2 as a soundtrack album. When lyrics were added to the melody, Andy Williams sang “Where Do I Begin” to no. 7 on the charts that same year.

The score almost didn’t happen. Lai initially turned down the assignment, he told the Los Angeles Times in 2001. But French actor Alain Delon, who had seen a cut of the film, called Lai and convinced him to delay his summer vacation.

Delon and producer Robert Evans flew to Paris with a print, screened it for him and, said Lai, “I came out of the screening incredibly moved. I went straight home, sat at my keyboard and wrote that theme that very night.”

Lai had already achieved a modicum of fame with his romantic theme for “A Man and a Woman,” French director Claude Lelouch’s art-house hit of 1966. The combination of Lai’s accordion and the wordless “da-ba-da-ba-da, da-ba-da-ba-da” vocals of a male-female duo struck a chord with record-buyers, propelling the soundtrack album to no. 10 on the American charts.

Director Lelouch became Lai’s greatest champion, collaborating with the composer on nearly 40 projects — many of them romantic in nature — including “Live for Life” (1967), “Love Is a Funny Thing” (1969), “Happy New Year” 91973), “And Now My Love” (1974), “Another Man, Another Chance” (1977), “Bolero” (1981), “Edith and Marcel” (1983), “A Man and a Woman, 20 Years Later” (1986) and their final film together, last year’s “Everyone’s Life.”

He worked for other English and French directors as well, scoring “I’ll Never Forget What’sisname” for Michael Winner (1967), “Mayerling” for Terence Young (1968), “Three into Two Won’t Go” for Peter Hall (1969), “Rider on the Rain” for Rene Clement (1970), “International Velvet” for Bryan Forbes (1978) and “Les cles du Paradis” for Philippe de Broca (1991). His albums for “Emmanuelle 2” (1975) and “Bilitis” (1977) were hits among European record-buyers.

In all, he scored more than 100 films. For American television, he scored the TV movie “Berlin Affair” (1970), the theme for “The Sex Symbol” (1974) and the Joan Collins miniseries “Sins” (1986), which sported a Carly Simon song written by Lai.

Lai was born in Nice, played accordion and piano, and while he was still in his 20s, settled in Paris’s Montmartre district. He soon became accompanist to the legendary chanteuse Edith Piaf. He began writing songs for her as well, and his total song output is now said to exceed 600.

Survivors include his wife and three children. The funeral is scheduled for Wednesday at 10 a.m. at the Cathedral Catherine Saint-Arson in Nice.

“It is with great sadness that I learn of the death of Francis Lai, this great composer from Nice,” Nice Mayor Christian Estrosi reported. “I will soon propose to his family to give his name to an emblematic place of our city.” Added Gilles Jacob, former president of the Cannes Film Festival: “His melodies had a crazy charm.”