Live coverage of a Proms concert by the Israel Philharmonic Orchestra was pulled last night after disruptions by protesters chanting 'Free Palestine'.
The BBC was forced to take the broadcast off air because of the outbursts during the event at London's Royal Albert Hall.
Gil Shaham was about to play Bruch's violin concerto conducted by Zubin Mehta when booing and shouting began.
Michael Stern, who was in the audience, said: 'There were four to five disruptions at the beginning of each piece.
'The protesters started singing in the middle of the performance. It was obviously rehearsed. They were singing in tune to Beethoven's Ninth.
'They are musicians not politicians, they are here to play. It's fair to make a protest outside but not to take it in. All of us paid good money to come here.'
It is believed that around 40 protesters bought seats, which would have cost them around £20 each.
Pomp: The Proms, normally a good-natured celebration of music
Radio 3 interrupted its live broadcast at 7.45pm before returning later. Coverage was cut off again an hour later following more protests.
Earlier the Palestine Solidarity Campaign had urged music lovers to boycott the concert and called for the BBC not to broadcast it.
One of the protesters, Professor Jonathan Rosenhead, of the London School of Economics, said: 'The orchestra is intimately connected with the Israeli state.
'We are saying not to forget the denial of human rights in Israel.'
A BBC spokesman said: 'We regret that as a result of sustained audience disruption within the concert hall which affected the ability to hear the music, tonight's Israel Philharmonic Orchestra Prom was taken off air.