Renowned soprano Montserrat Caballe, who brought opera into the pop charts by singing Barcelona with Freddie Mercury three decades ago, died aged 85 early on Saturday, hospital officials said.

The Spanish singer, who was born in the Catalan capital, had been in ill health for a number of years and had been admitted to hospital in mid-September, an official said. She died in Sant Pau hospital in Barcelona.

The Gran Teatre del Liceu opera house in Barcelona, where Caballe performed more than 200 times, described her as “one of the most important sopranos in history”.

Spanish tenor Jose Carreras said she possessed a voice of great range, combined with a flawless technique.

“Of all the sopranos I've heard live in the theatre, I've never heard anyone singing like Caballe,” Carreras said in a radio interview with Catalunya Radio. Spain’s royal family called her“the great lady of the opera, a legend of universal culture, the best among the best”.

“Her personality and her unique voice will always be with us,” the royals said in a tweet.

Caballe released the song Barcelona with the Queen frontman Mercury in 1987 — and it was used again during the 1992 Barcelona Olympics, a year after Mercury’s death.

Renowed for her performances of Italian opera, she also worked with the late tenor Luciano Pavarotti.

Caballe was considered one of the finest modern exponents of the “bel canto repertoire”, Spain’s culture minister Jose Guirao said on Saturday. “Her loss leaves a huge void,” he said.

Caballe’s almost 60-year career took her from Basel to New York. She began in the Swiss city in 1956, as Mimi in La Boheme, then joined the Bremen Opera, where she sang from 1959 to 1962, in a wide variety of roles.

Wider international recognition came in 1965, when she appeared in a performance of Donizetti's Lucrezia Borgia at Carnegie Hall in New York.