Polish musician caught a member of the audience filming him on a mobile phone when he was performing in Essen, German

One of the world's leading concert pianists angrily exited a performance on Monday evening saying YouTube was "destroying music" after he caught a member of the audience filming him on a mobile phone.

Krystian Zimerman, from Poland, was distracted by the concertgoer while in the middle of playing Karol Szymanowksi's Variations on a Polish Theme in B Minor at the Ruhr piano festival in Essen.

Still playing, he raised his gaze towards the audience member, who was sitting in a balcony seat above him, and said: "Would you please stop that?"

But while Zimerman, 56, resumed playing the work he had clearly lost his concentration, and left the stage shortly afterwards, evidently agitated.

On returning, he told the audience that he had lost many recording projects and contracts because music managers had told him: "We're sorry, that has already been on YouTube." "The destruction of music because of YouTube is enormous," he added.

He continued to perform, but declined to return at the end of the concert for an encore, despite a rapturous response. He also cancelled a reception after the concert.

Franz Xaver Ohnesorg, the festival's director, said he felt a great deal of sympathy towards Zimerman, one of the star performers. "What happened is theft, pure and simple," he told German media. "It cuts particularly deeply when the artist is of a sensitive nature."

Representatives of the classical music world said Zimerman's eruption was understandable and welcomed the fact he had highlighted a growing problem. "People filming concerts on their smartphones is a problem, and the person who did it deserves to be hounded out of the concert hall," said German pianist Sebastian Knauer, artistic director of the Mozart@augsburg festival, who is due to perform at the festival next week. "You see stuff on YouTube, and you think it's not possible that people take such liberties."

Anke Demirsoy, spokeswoman for the 25-year-old Ruhr Piano Festival, which is the largest worldwide gathering of the international pianist elite, said organisers would be discussing what steps it might take to curtail the use of smart phones during concerts in future.

"It's hard to catch culprits, because smart phones are so small they can quickly disappear back into bags and it's hard to pick people out in the dark. Clearly some people think buying a concert ticket entitles them to the film rights as well."

Zimerman, who first attracted international attention in 1975 when he won the International Chopin competition in Warsaw, is considered one of the greatest living pianists, with a reputation for planning the relatively few concerts he performs each season with great meticulousness. He has won critical acclaim in particular for his recordings of Rachmaninov, Brahms and Liszt.

Monday night was not the first time he has interrupted a concert. In 2009, while performing in LA, he delivered a quiet but forceful denunciation of US foreign policy from the stage, which caused some audience members to boo and leave the Walt Disney Concert Hall. In his short speech, he criticised US plans to establish a missile defence shield in his native Poland. Prior to that, he made headlines for non-musical reasons after his Steinway piano was confiscated at JFK airport by US authorities shortly after the 9/11 attacks, who objected to the smell of the glue with which it had been assembled. They went on to destroy it.