The rock star Peter Gabriel and film-maker Ken Loach are among 21,000 people who have signed an open letter to David Cameron, the British prime minister, demanding an immediate halt to the arms trade between the UK and Israel.

Israelis in Tel Aviv’s Rabin Square light candles for Palestinians killed in Gaza on 26 July

The letter was posted on the Palestine Solidarity Campaign’s website last week and gathered 21,000 signatures in just two days.