Al Martino, who died on Oct 13 aged 82, was a great postwar Italian-American crooner who rose to even further fame with his role as the singer Johnny Fontane in The Godfather, the 1972 blockbuster movie starring Marlon Brando; he also sang the UK first number one record.

The character of Fontane – a busted flush who seeks the intervention of the Mafia to revive his career – is often said to have been based on Frank Sinatra, who had long been known to have mob connections; but equally there were parallels with Martino's own life story.

Indeed, his friend Phyllis McGuire – one of the singing trio The McGuire Sisters and the girlfriend of the mobster Sam Giancana – told Martino before the film was made: "I just read a book, [Mario Puzo's] The Godfather. Al, Johnny Fontane is you – and I know you can play it in the movie."

Martino later claimed that he contacted the film's producer, Al Ruddy, who offered him the part, despite the fact that he had no acting experience. The crooner arranged to be released from a contract to sing at the Desert Inn in Las Vegas (costing him an estimated $250,000), but was then rejected for the Fontane role by the director, Francis Ford Coppola, in favour of Vic Damone.

According to Martino, Coppola was eventually outflanked, after the singer used mob connections to pressure the director in a manner that could have come from the film: "Didn't the Don send Tom Hagen to convince Jack Woltz that Johnny Fontane must be in the movie? Isn't it similar to what I did? Woltz didn't want Johnny, and Coppola didn't want me. There was no horse's head, but I had ammunition... I had to step on some toes to get people to realise that I was in the effing movie. I went to my godfather, [Mafia boss] Russ Bufalino."

Damone subsequently backed out of the project, leaving the way clear for Martino.

Whether Martino was actually the right man for the role is questionable. Johnny Fontane is the godson of Brando's Mafia boss character, Don Vito Corleone. As Fontane weeps because a movie producer refuses to give him a role, Brando barks at him: "You can act like a man!" and slaps him in the face. According to another member of the cast, the slap was Brando's attempt to extract some emotion from Martino's wooden expression.

Martino also sang the 1972 film's title score, I Have but One Heart (O Marenariello), also known as The Love Theme From The Godfather.

His appearance in the movie came at a time when, as a singer, he appeared to be past his peak. For two decades he had produced a string of hit records, starting in 1952 with Here In My Heart, which had the distinction of going to No 1 in the first ever UK singles chart (earning him a mention in The Guinness Book of Records), remaining in the top spot for nine weeks.

Before releasing the record Martino had heard that Mario Lanza – whom he had known since their childhood in Philadelphia – was planning to cut his own version of the song. Knowing that this would eclipse his debut single, he pleaded with his friend to leave the field clear. Lanza agreed.

The success of Here in My Heart brought Martino a contract with Capitol Records, and in 1953 he followed up with three more hits – Take My Heart, Rachel, and When You're Mine.

There was, however, a price to pay for his new stardom. In 1952, when Here in My Heart had been No 1 in America, two thugs turned up at the house of Martino's manager demanding to buy the young singer's contract. According to Martino, when they threatened his manager's life, "he just gave them my contract for free".

Martino claimed that when he cut up rough he was beaten up by two men at the 500 Club in Atlantic City. They produced a promissory note for $80,000 – "future earnings, the money we could've made off of you" – which he signed. He then fled to Britain.

Al Martino was born Alfred Cini in Philadelphia on October 7 1927, the son of Italian immigrants who ran a masonry business, and he began his working life as a bricklayer. Singing, however, was his passion from a young age, and he idolised Perry Como and Al Jolson. Another who inspired him was his friend Alfredo Cocozza, six years his senior, who as Mario Lanza was to become one of the biggest singing stars of his era.

During the Second World War Martino served with the US Marines, taking part in the invasion of the Pacific island of Iwo Jima, during which he was wounded. He then embarked on his showbusiness career, calling himself Martino (his mother's maiden name) and performing in Philadelphia nightspots. In 1948 he moved to New York, where he won a television talent show and a recording contract with the independent, Philadelphia-based label BBS.

Martino's hasty departure from the United States in 1952 was the start of six years "exile" in Britain, where he made a number of records and appeared at the London Palladium. On one occasion, after performing at the Palladium, Martino went to a party at the Dorchester hotel where he chatted to Winston Churchill.

In 1958 Martino was able to return to America thanks to the good offices of Angelo Bruno, the so-called "Gentle Don". By now the advent of rock and roll was denting enthusiasm for crooners, and Martino found success harder to come by. But he recorded albums such as The Exciting Voice of Al Martino (1962), which he financed himself, and The Italian Voice of Al Martino.

Then, in 1963, he came up with a hit single in I Love You Because, the first of a string of hits over the next 10 years. Among these was the single Spanish Eyes (1965, written by Bert Kaempfert), which reached No 5 in Britain when it was re-released in 1973 and is said to be one of the 50 most-played songs in the world. In 1976 his disco remix of the Italian pop song Volare was another huge hit, particularly in Europe.

Martino reprised his role as Johnny Fontane in The Godfather Parts II and III. In later years he was mostly occupied with performing at clubs and casinos, but in 2000 he released the album Style. In 2006 he returned to the screen as an ageing crooner in the film Cutout.