King Charles III's final day in Kenya on Friday was hit by heavy rains and floods as he toured the historic heart of the Indian Ocean city of Mombasa.

The inclement weather derailed plans for Charles and Queen Camilla to ride in an electric tuktuk to Fort Jesus, a 400-year-old UNESCO World Heritage site in Mombasa's Old Town.

Instead, the royal couple briefly posed for photographs inside the three-wheeler vehicle, which was decorated in a bold African pattern and a Union Jack logo.

Kenya's coast and other parts of the country have been battered by torrential rains and sometimes raging floods in recent days.

The UN's humanitarian agency, OCHA, said last month that eastern Africa would likely encounter heavier than normal rains over the October-December period because of the El Nino phenomenon.

El Nino is a naturally occurring pattern associated with increased heat worldwide, as well as drought in some parts of the world and heavy rains elsewhere.

King Charles has long been a fervent environmentalist and his programme on the four-day state visit to Kenya has focused on green issues, as well as support for creative arts, technology and young people.

His host, President William Ruto, has sought to put himself at the forefront of African efforts to combat climate change.

- 'No chance to greet him' -

Some in Mombasa, which was Kenya's capital for some years under colonial rule, voiced disappointment they did not meet the royals.

"The king has come to our region but we have not had a chance to see him or even greet him," said tour guide Martin Mvurya, 42.

"I only saw the face of the king as they got into the car. I thought he would take time to address us," added a 25-year-old unemployed man who gave his name only as Abdala.

The visit has however stirred mixed emotions in the former colony, with calls for the king to apologise for Britain's brutal crackdown on Kenya's independence struggle.

At a state banquet on Tuesday, the 74-year-old monarch said the "wrongdoings of the past are a cause of the greatest sorrow and the deepest regret," but stopped short of an apology.

"There were abhorrent and unjustifiable acts of violence committed against Kenyans as they waged... a painful struggle for independence and sovereignty. And for that, there can be no excuse," he said.

At least 10,000 people -- mainly from the Kikuyu tribe -- were killed when colonial-era authorities brutally suppressed the Mau Mau uprising between 1952-1960, although some put the true figures much higher.

Tens of thousands more were rounded up and detained without trial in camps where reports of executions, torture and vicious beatings were common.

During his stay in Nairobi, the king held private talks with descendants of Dedan Kimathi and Mekatilili wa Menza -- two influential leaders of the independence struggle.

On Friday, Charles visited Mombasa's Mandhry Mosque and the Memorial Cathedral, where he joined an interfaith meeting, before the royal couple later departed for home.