A leading judge at the international court of justice has said the UK will no longer be able to ignore the growing calls for reparation for transatlantic slavery. Judge Patrick Robinson, who presided over the trial of the former Yugoslav president Slobodan Milošević, said the international tide on slavery reparations was quickly shifting and urged the UK to change its current position on the issue. “They cannot continue to ignore the greatest atrocity, signifying man’s inhumanity to man. They cannot continue to ignore it. Reparations have been paid for other wrongs and obviously far more quickly, far more speedily than reparations for what I consider the greatest atrocity and crime in the history of mankind: transatlantic chattel slavery,” Robinson said. “I believe that the United Kingdom will not be able to resist this movement towards the payment of reparations: it is required by history and it is required by law.” Robinson spoke exclusively to the Guardian ahead of Unesco’s Day for Remembering the Transatlantic Slave Trade and Abolition. He is scheduled to make the keynote address on Wednesday at the London mayor’s office to mark the day. The event follows the key role that Robinson played in writing and compiling the Brattle Group Report on Reparations for Transatlantic Chattel Slavery, which was published in June. The report, which has been described as the most comprehensive state-to-state reparations analysis, identifies the reparations that are due in respect of 31 countries in which transatlantic slavery was practised. The study estimates that trillions of dollars are owed in reparations to countries affected by transatlantic slavery. The report, which was published by the University of the West Indies after a symposium held by the American Society of International Law, concludes that the UK alone is required to pay a sum of $24tn (£18.8tn) as reparations for transatlantic slavery in 14 countries. Of that sum, about $9.6tn is due to Jamaica. The report uses calculations made by the Brattle Group, which factors in the wealth and GDP amassed by countries that enslaved African people. When asked if the high figures came as a surprise, Robinson said no. “These calculations are not over a period of five years or 10 years. They cover the entire duration of transatlantic chattel slavery, which means they cover hundreds of years. What is more, reparations have never been paid. So the calculations begin from day one of transatlantic chattel slavery, that is hundreds of years; and that alone explains the high figures.” To address the figures, Robinson said the report proposed that payments be made over a longer period of time, between 10 and 25 years, rather than instantly. At the launch of the report at the University of the West Indies in Kingston Jamaica, PJ Patterson, a former prime minister of Jamaica, reportedly said that reparations were owed to Jamaica and the other countries affected by transatlantic slavery, and would not rule out bringing the issue to courts. On achieving reparations through international courts, Robinson said: “It’s possible, but frankly, I think the greater probability is for a settlement on a political diplomatic basis, which takes into account the relevant legal considerations … But I don’t rule out court proceedings.” In April, the UK prime minister, Rishi Sunak, refused to apologise for the UK’s role in the slave trade or to commit to paying reparations. Robinson said: “I have the highest regard for the prime minister of the United Kingdom, but I believe the stance that he has taken is regrettable and I very much hope that he will reconsider it. “The tide is changing, the political tide, the global tide is moving. The United Kingdom – [including] both principle parties, the Conservative party and the Labour party and the other parties, which are just as important – need to take into account that movement is a movement in favour of reparations. The transatlantic chattel slavery is the greatest atrocity in the history of humankind without parallel for its brutality, without parallel for its length over 400 years, without parallel for its profitability.” Robinson was born in Sheffield, Jamaica, in 1944. After graduating from university, he worked as a prosecutor in Jamaica. He worked briefly at the Ministry of Foreign Affairs, and for 26 years in the attorney general’s department. “I was responsible for advising the government on international law matters. I became a member of the International Law Commission. I became a member of the Inter-American Commission on Human Rights and its president, and I became a member and president of the International Criminal Tribunal for Yugoslavia, and actually presided over the trial of Slobodan Milošević. Then in 2015, I was elected to the international court of justice.” He said that everything he did in life had been inspired by his father, who was a headteacher of an elementary school in Jamaica. “My father’s mantra was that the cane cutter’s child deserves the same educational opportunities as the child of the busher, who is the overseer.” He added: “I have spent with a great sense of deficit in relation to the public service that my father gave. And this endeavour that I’ve been involved in for the past four years is really an attempt on my part, to try to reduce that deficit. I see it as a kind of service for the descendants of the enslaved not only in Jamaica and the Caribbean, but wherever transatlantic chattel slavery was carried out.”