The letter also denounces the United States, the European Union and several developing countries for what it describes as their "complicity" in weapons sales and other military support in the attack that killed 160 Palestinians, many of them civilians, including about 35 children.
The 52 signatories include the Nobel peace laureates Mairead Maguire and Adolfo Pérez Esquivel; film directors Mike Leigh and Ken Loach; author Alice Walker; US academic Noam Chomsky; Roger Waters of Pink Floyd; and Stéphane Hessel, a former French diplomat and Holocaust survivor who was a co-author of the universal declaration of human rights. The other signatories include John Dugard, a South African jurist and former United Nations special rapporteur in the occupied territories; Luisa Morgantini, former president of the European Parliament; Cynthia McKinney, a former member of the US Congress; former South African Cabinet member Ronnie Kasrils; and the dramatist Caryl Churchill.
"Horrified at the latest round of Israeli aggression against the 1.5-million Palestinians in the besieged and occupied Gaza Strip and conscious of the impunity that has enabled this new chapter in Israel's decades-old violations of international law and Palestinian rights, we believe there is an urgent need for international action towards a mandatory, comprehensive military embargo against Israel," the letter says.
"Such a measure has been subject to several UN resolutions and is similar to the arms embargo imposed against apartheid South Africa in the past."
The letter accuses several countries of providing important military support that facilitated the assault on Gaza. "While the US has been the largest sponsor of Israel, supplying billions of dollars of advanced military hardware every year, the role of the European Union must not go unnoticed, in particular its hefty subsidies to Israel's military complex through its research programmes.
"Similarly, the growing military ties between Israel and the emerging economies of Brazil, India and South Korea are unconscionable given their nominal support for Palestinian freedom," it says.
The letter opens with a quote from Nelson Mandela: "For to be free is not merely to cast off one's chains, but to live in a way that respects and enhances the freedom of others."