Italian conductor Claudio Abbado, former musical director of La Scala, has died at the age of 80.
He died in Bologna after a long illness, said Raffaella Grimaudo, spokeswoman for the Bologna mayor's office.
Abbado, who was appointed senator for life in Italy last year, had cancelled several recent performances and appearances due to ill health.
He also conducted the London Symphony Orchestra (LSO) between 1979 and 1988.
He won plaudits for his LSO concerts of his favourite composer, Gustav Mahler.
He was also musical director of Vienna's Staatsoper from 1986 to 1991 and a guest conductor at the Chicago Symphony Orchestra.
In 1989, Abbado was elected head of the Berlin Philharmonic by its members, where he worked until 2002.
"The death of Claudio Abbado leaves a huge hole in the world of classical music," said Radio 3 controller Roger Wright, describing him as "one of the most important conductors of his generation".
He praised his "gentle manner, combined with a steely determination only to offer high quality music making, which delivered so many remarkable performances and recordings."
Mark Wilkinson, president of record label Deutsche Grammophon, said: "The world has lost one of the most inspiring musicians of our era, a man who put himself entirely at the service of the music he conducted and, in doing so, made listeners feel that they were hearing it properly for the very first time."
Abbado made his first recording for Deutsche Grammophon in 1967, and his last in 2013.
Abbado was born into a musical family in Milan in 1933 and trained at the Milan Conservatoire before studying under Hans Swarowsky in Vienna.
His career began at La Scala in 1960 and he went on to become musical director of the famous opera house until 1986, before his work with Vienna's state opera and the Berlin Philharmonic.
In 1997, Abbado won a Grammy Award in the best instrumental soloist performance (with orchestra) category.
In 2012, he was voted into the Gramophone Hall of Fame and awarded the conductor prize at the Royal Philharmonic Society (RPS) Music Awards.
The latter prize was given for his concerts with the Lucerne Festival Orchestra at the Royal Festival Hall in 2011.
The RPS praised Abbado, saying each of his concerts was "a performance of indelible, life-changing moments".
"His extraordinary, revelatory concerts with the Lucerne Festival Orchestra... changed perceptions, and raised the bar once again on what it is possible for a group of musicians to achieve."
Ahead of that concert, Abbado told BBC Radio 4's Today programme that he was a "perfectionist" and that "without music, the world would be a terrible place."
He was passionate about young musicians and founded youth orchestras across Europe.
La Scala said illness forced Abbado to cancel two concerts in 2010 that were to have marked his return to the Milan opera house for the first time in 25 years, and to celebrate the 50th anniversary of his conducting debut.
Abbado had suffered health problems for many years, resigning from his Vienna Opera post for health reasons in 1991 and then undergoing stomach cancer surgery in 2000.