Britain's tarnished colonial past took centre stage in Kenya on Tuesday as King Charles began a four-day state visit, poised to acknowledge "painful aspects" of the countries' long shared history as local leaders press demands for reparations.

Accompanied by Queen Camilla on his first visit as monarch to a former colony, Charles arrived in the capital Nairobi overnight.

On a rainy morning, he was welcomed to the Presidential Palace by a 21-gun salute and a guard of honour and, accompanied by President William Ruto, planted trees in the palace grounds. The royal couple then laid a wreath at the Tomb of the Unknown Warrior in Uhuru Gardens, where Kenyan declared independence in December 1963.

Charles' visit comes at a time when former colonies are demanding that Britain do more to recognise the abuses of its colonial past. Some - notably Barbados and Jamaica - have been re-evaluating their ties to the monarchy.

While still heir to the throne, Charles surprised many at last year's summit of the Commonwealth - a voluntary association of countries that evolved from the British Empire - by acknowledging slavery's role in the organisation's roots.

Many citizens of former British colonies - including leaders of Kenya's Nandi people - want Charles to go further by directly apologising and endorsing reparations for colonial-era abuses, including torture, killings and widespread expropriation of land, much of which remains in British hands.

Buckingham Palace said the visit would "acknowledge the more painful aspects of the UK and Kenya's shared history, including the Emergency (1952-1960). His Majesty will take time ... to deepen his understanding of the wrongs suffered in this period by the people of Kenya."

'AFTER APOLOGIES... REPARATION'

During the 1952-1960 Mau Mau revolt in central Kenya, some 90 000 Kenyans were killed or maimed and 160 000 detained, the Kenya Human Rights Commission (KHRC) has estimated.

The UK government has previously expressed regret for those abuses and agreed a 20-million pound settlement in 2013.

Nandi King Koitalel Arap Samoei led a decade-long rebellion until he was assassinated by a British colonel in 1905. In the ensuing years, the British confiscated most of his people's land and cattle.

Samoei's great-grandson Kipchoge araap Chomu credited the British with contributions to Kenya like education and public health systems but said historical injustices must be remedied.

"We have to demand public apology from the government of the British...," he told Reuters. "After apologies, we also expect a reparation."

Charles also plans to meet entrepreneurs from Kenya's bustling tech scene, tour wildlife facilities and travel to the southeastern port city of Mombasa.