The Prime Minister has expressed his wish that the British Jewish community have a "happy and peaceful Rosh Hashanah" and vowed to defend Israel against its enemies.
David Cameron said he wanted to "pay tribute to the tremendous contribution your community has made to this country and continues to make each year".
Mr Cameron, who has on previous occasions spoken about his Jewish roots, referred to his great-great-grandfather, Emile Levita. A German émigré banker, he became a British citizen in 1871, then married out and sent his sons to Eton.
Mr Cameron said he was incredibly moved by Mr Levita's story. "It made me appreciate all the more what the Jewish community has brought to Britain," he said.