Not long into my meeting with Roberto Alagna I begin to wonder whether the Franco-Sicilian tenor doesn’t identify a little too closely with whichever role he happens to be singing at the time. I arrive at the allotted swanky bar in the allotted swanky hotel in Paris clutching the last interview Alagna gave a British newspaper, back in 2004 when he was playing the reckless Faust, who makes an unwise pact with Satan to regain his youth. Then he practically turned cartwheels for his interviewer, confessed he could be be “a little devil” and happily accepted that both he and Goethe’s antihero shared an insouciant disregard for moderation.

Now the 45-year-old tenor is reading from a different script. Alagna has just finished a run of Aida at the Liceu opera house in Barcelona, singing the Egyptian soldier Radames; he had recently also jumped into the role at short notice at the Metropolitan Opera in New York, to huge acclaim. And so he has taken to heart a phrase adapted from the character’s first scene. “I’m not a warrior,” he insistently repeats during the interview, a line he delivers with wounded pride. If he sings his all-Verdi concert at the Barbican next week with as much emotion, he will have us eating out of the palm of his hand.

But, just as Radames marches into battle shortly after professing his doubts on the subject, so Alagna starts the counter-attack early. “I don’t do competition or fights,” he insists, amid a tirade about how opera companies across the world only ever pick on him and his glamorous wife (the temperamental Romanian soprano Angela Gheorhgiu) to drum up publicity for themselves. “It’s very good for the media also,” he says. “If you don’t have this kind of scandal, then we are not interesting.”

Perhaps, then, we should stick to the facts. In December 2006, in response to jeers from some of the audience after his first aria, Alagna walked off the stage of La Scala in Milan just minutes into his second performance as Radames, and was replaced by an understudy (Antonello Palombi), who was pushed on stage and had to finish the act in jeans and a T-shirt. Alagna was fired from all remaining performances and released from any future contracts with the house. The walkout provoked headlines around the world.

He’s still fuming. “First, it was a big mistake by La Scala. I had health problems, and everybody at La Scala knew I would go away and I would return, after five minutes drinking water with some sugar. I told them that before in my dressing room – I said if something happens to me tonight, I will go outside and I will return. And they betrayed me.”

Alagna’s allegation is nothing less than an audacious coup on the part of La Scala to substitute Palombi in his stead. “When I went away I had no time to tell them anything, because they put this guy [Palombi] on directly, and after that it was impossible.”

This conflicts with Alagna’s first comment in 2006 on the fracas, made to the Italian paparazzi: “The audience didn’t understand and that’s why I left.” And even now, while insisting it was not the catcalls that drove him off the stage, he makes his opinions pretty clear about La Scala’s notorious loggionisti, the house’s most diehard opera fans, who regard booing singers as de rigueur.

“Why because you have paid for your tickets do you have a right to insult somebody? Do you think when a singer is on stage you will help him to sing better if you are insulting him? I don’t think so.”

So we move to fracas numéro deux: Alagna’s recent success in New York last autumn. Eager to take up a challenge, he learnt the part of Pinkerton in Madama Butterfly in two days, as well as jumping into Aida and singing Romeo in Gounod’s Roméo et Juliette. The only problem was that he wanted Gheorghiu to come from Chicago (she was rehearsing for La Bohème at the Lyric Opera) to cheer him on. Chicago refused, she went anyway, and, yes, duly got fired.

Alagna’s explanation of the affair hardly brims with politesse. “She asked one time, they said no. She asked a second time – no. At the third time she said Vafanculo [literally, “go f*** yourself”]. You know how many times you sing La Bohème without rehearsal in the world?” For a man who talks about “serving the composer” as his highest priority, Alagna’s blithe disregard for his wife’s professional obligations to Puccini as well as her employers smacks more than a little of hypocrisy.

So I try one last time: given the level of controversy that now swirls around Alagna and Gheorghiu, wouldn’t keeping a lower profile, trying not to provoke rows, and just, generally, trying one’s hardest simply to get on with it, be the best strategy? “I assure you – we are the least problematic singers in the world.”

I guess we’ll agree to disagree. At least Alagna proved the doubters wrong with his stunning successes in New York. Plenty of critics (including me) had criticised Alagna at the time of the La Scala debacle – not just for walking out, but for singing the notoriously hefty role of Radames in the first place. What, we wondered, had happened to the light French tenor who burst on the scene back in the mid 1990s with such élan, prompting the opera world to acclaim the rise of the “fourth tenor”?

The answer is perhaps that, for all his rough and ready training (Alagna was already singing Verdi for Glynde-bourne Touring Opera in 1988, at the age of 25), he says he knows his own voice better than anyone else. Looking beyond next week’s frighteningly ambitious concert, next season he will continue his explorations of heavy Verdi by singing one of the most difficult roles in the entire Italian repertoire, Manrico in Il trovatore, at Covent Garden. “My voice, it’s lyrical, and in the history, all the lyrical tenors – Caruso, Pavarotti, Carreras, Domingo, they sang the same repertoire as me. But it’s very strange, because if you want to do something it’s never for you. Maybe you can advise me on what to sing.”

Chalk up Alagna’s supreme bullishness to the Sicilian in him – it certainly looms larger than the suave Frenchman. In fact, Alagna has just written his first volume of autobiography (Je ne suis pas le fruit du hasard, or “I did not happen by accident”), in which he explores the world of his poor Italian grand-parents both before and after they moved to the grotty Parisian suburb in which the tenor grew up. “Music was the thread of my family for generations,” he says. “My grandfather was born in New York, he was great friends with Caruso, and he sang for the great Mafia families.” And all were as, shall we say, hot-blooded? “Of course – an artist must be very temperamental, but also very sensitive.”

Some of the latter comes through once we’ve left the choppy waters of La Scala or Chicago behind. Singing with Gheorghiu, he says, is terrific – and he wants to do it more often than they currently manage. “Maybe at first it was not good to do everything together,” he admits, “but now it’s not good to do so little.” For when the couple are on stage together, “it’s beautiful, because you discover your wife each night in another opera. It’s like you have 1,000 wives in one.”

Otherwise, Roberto Alagna beams with the simple thrill of being Roberto Alagna. Immediately after I meet him he is, after all, off to have his waxwork created at the famous Musée Grévin – the ultimate in French adulation (at least, until Alagna tops it a few weeks later by getting the Légion d’Honneur). “It’s a great honour for me, just the simple son of migrants, and now at the Musée Grévin? Sometimes I think, during my sleepless nights, thank you God – you’re very kind!”

Roberto Alagna sings at the Barbican, London EC2, on May 2 (www.barbican.org.uk 020-7638 8891). He appears in a high-definition relay of Aida from La Scala in selected UK cinemas (www.myvue.com/opera)

Explore Stage

• Theatre

• Comedy

• Opera

• Dance

Editor's choice

• Gordon Brown’s secret to stayin’ alive
• What’s up with Woody?
• Can Cannes get serious?