Pro-Palestinian protesters interrupted the Philadelphia Orchestra's Thursday night performance in Brussels, urging the orchestra to cancel the upcoming Israel leg of its tour.

The protesters broke into a performance of the Brahms Piano Concerto No. 1 in D Minor with chants of "free, free, Palestine," and after about 30 seconds, music director Yannick Nézet-Séguin stopped conducting and the music came to a halt, said cellist John Koen. Security removed the protesters, and the concert resumed about 25 minutes later, he said.

An orchestra spokeswoman said she was unsure of the number of protesters, but she believes two were removed from the hall.

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The orchestra leadership said it would be assessing next steps. "We're in talks with the other presenters [in the other cities on the tour] to speak about security measures that might be taken," said orchestra spokeswoman Ashley Berke.