The authors' letter is entitled Writers Demand Immediate Gaza Ceasefire and organised by writers Horatio Clare, Kapka Kassabova and Monique Roffey.
It notes that Amnesty and Human Rights Watch, as well as independent experts appointed by the United Nations human rights council, have, it says, "clearly identified genocide or acts of genocide in Gaza, enacted by the Israel Defence Force and directed by the government of Israel".
The authors call for the "immediate unrestricted distribution of food and medical aid in Gaza by the UN", and a ceasefire "which guarantees safety and justice for all Palestinians, the release of all Israeli hostages, and the release of the thousands of Palestinian prisoners arbitrarily held in Israeli jails".
Sanctions should be imposed, the letter argues, if the Israeli government does not take action.
While taking this stand, the authors also used the letter to "assert without reservation our absolute opposition to and loathing of antisemitism, of anti-Jewish and anti-Israeli prejudice".
The letter continued: "We reject and abhor attacks, hate and violence – in writing, speech and action – against Palestinian, Israeli, and Jewish people in all and any form. We stand in solidarity with the resistance of Palestinian, Jewish, and Israeli people to the genocidal policies of the current Israeli government."
Organisers said the letter was composed with input from a dozen British writers, based on another letter published in France's Liberation newspaper earlier this week, which was signed by 300 French-speaking writers.