Guyana's President Irfaan Ali has asked descendants of European slave traders to make reparations to correct past wrongs and demanded that traders and enslavers face posthumous prosecution for crimes against humanity.

Ali's remarks came ahead of the formal apology of descendants of Scottish 19th-century sugar and coffee plantation owner John Gladstone, father of four-time UK Prime Minister William Gladstone.

The South American President indicated that reparations were "a commitment to righting historical wrongs."

"The transatlantic slave trade and African enslavement were an affront to humanity itself. The heinousness of this crime against humanity demands that we seek to right these wrongs," he pointed out.

Caricom countries, a 15-nation Caribbean trade group including Guyana, have hired a British legal firm to investigate their claim for financial reparations from the United Kingdom and other European countries. According to the trade bloc, it has been informed that its case is solid and should be pursued.

"The descendants of John Gladstone must now also outline their plan of action in line with the Caricom … plan for reparatory justice for slavery and indentureship," Ali underscored.

Six of Gladstone's descendants, including a number of historians, arrived in Guyana on Thursday to mark the 200th anniversary of the 1823 slave rebellion, which historians believe cleared the path for slavery abolition.

On Friday, the family attended a ceremony at the University of Guyana -- built on plantation lands "where the revolutions were enacted," according to the institution.

"It is with deep shame and regret that we acknowledge our ancestors’ involvement in this crime and with heartfelt sincerity, we apologize to the descendants of the enslaved in Guyana," Charles Gladstone, a descendant of Gladstone, told the audience at the ceremony that was not attended by President Irfaan Ali nor other senior government officials.

"In doing so, we acknowledge slavery’s continuing impact on the daily lives of many," he added.

Gladstone revealed that his family would establish a fund for different unspecified initiatives across Guyana as part of a “meaningful and long-term relationship between our family and the people" of the country.

"In writing this heartfelt apology, we also acknowledge Sir John Gladstone’s role in bringing indentured laborers to Guyana, and apologize for the clear and manifold injustices of this," he expressed.

Gladstone called on the British government to begin "meaningful discussions" with Caricom. "We also urge other descendants of those who benefited from slavery to open conversations about their ancestors’ crimes and what they might be able to do to build a better future."

Ali had praised Gladstone's family's apology, calling it "an acknowledgment of the cruel nature of African enslavement and indentureship in Guyana and an act of contrition that paves the way for justice."

"The Gladstone family has admitted that it benefited from African enslavement and indentureship on the Demerara and other plantations owned by its patriarch, John Gladstone," he added.

The University of Guyana also launched its International Centre for Migration and Diaspora Studies at the ceremony, in collaboration with Guyana's national reparations committee and Heirs of Slavery, a lobby group founded by British families with ancestors who were traders and enslavers.

While a few nations, notably the Netherlands, have issued official apologies for slavery, UK Prime Minister Rishi Sunak declined to apologize or commit to making reparations in April.

Read more: UK cannot ignore calls for slavery reparations: UN judge