The London Philharmonic Orchestra (LPO) has suspended four of its musicians for up to nine months after they signed a letter calling on the BBC to cancel a Proms concert by the Israel Philharmonic Orchestra.

Cellist Sue Sutherley and violinists Tom Eisner, Nancy Elan and Sarah Streatfeild were among 24 musicians who signed a letter that appeared in The Independent newspaper two days before the concert. The four players were identified next to their names as being members of the LPO.

The letter referred to the Israel Philharmonic Orchestra as 'perhaps the prime asset' in a campaign through which 'denials of human rights and violations of international law are hidden behind a cultural smokescreen'. It also said: 'Israel's policy towards the Palestinians fits the UN definition of apartheid.'

In a joint statement, the LPO's chief executive, Timothy Walker, and its chairman, Martin Höhmann, said: 'The political views of LPO players are a private matter for players. The LPO has no political or religious affiliations and strongly believes in the power of music to bring peace and harmony to the world. The orchestra would never restrict the right of its players to express themselves freely; however, such expression has to be independent of the LPO itself and must not be done in any way that associates them with the LPO.'

They added: 'The company has no wish to end the careers of four talented musicians but the board's decision in this matter will send a strong and clear message that such actions will not be tolerated by the LPO.'