Britain's King Charles said on Friday the Commonwealth should acknowledge its "painful" history, as African and Caribbean nations continue to advocate for reparations for the country's role in the transatlantic slave trade.

Britain's handling of its involvement in the trans-Atlantic slave trade is seen by many as a litmus test for the Commonwealth's adaptation to a modern-day world.

King Charles III arrived in Samoa on Wednesday to preside over the gathering of Commonwealth presidents and prime ministers for the first time as head of the monarchy.

Britain's King Charles and Queen Camilla flew into Samoa late on Wednesday, for a visit during which the monarch will be offered the title of high chief and attend a summit of Commonwealth nations, following a six-day tour of Australia.

During a speech Friday, King Charles III said the Commonwealth should acknowledge its "painful" history with transatlantic slavery.