APIA, Samoa — King Charles said Friday that the Commonwealth should acknowledge its “painful” history, as African and Caribbean nations push for reparations for Britain’s role in transatlantic slavery.

Representatives of 56 countries, most with roots in Britain’s empire, are attending the Commonwealth Heads of Government Meeting that began in Samoa on Monday, with slavery and the threat of climate change emerging as major themes.

“I understand from listening to people across the…