Kenneth Kaunda, Zambia's first president and one of the last of the generation of African leaders who fought colonialism, has died aged 97.

Confirming Kaunda's death, his son Kambarage said he died at a military hospital in Lusaka where he was being treated for pneumonia.

“I am sad to inform (members) we have lost Mzee (the old man). Let’s pray for him,” Kambarage said on the late president’s Facebook page.

In the 1950s, Kaunda was a key figure in what was then Northern Rhodesia's independence movement from Britain.

He became president following independence in 1964.

Kaunda ruled Zambia from 1964, when the southern African nation won its independence from Britain, until 1991, and afterwards become one of Africa’s most committed activists against HIV/AIDS.

Although Zambia’s copper-based economy fared badly under his long stewardship, Kaunda will be remembered more for his role as an anti-colonial fighter who stood up to white minority-rule in southern African countries including Angola, Mozambique, Namibia, South Africa and Rhodesia, now Zimbabwe.

Reacting to news of Kaunda's demise, Zambian President Edgar Lungu said the country was mourning "a true African icon".

"I learnt of your passing this afternoon with great sadness," he wrote on Facebook. "On behalf of the entire nation and on my own behalf I pray that the entire Kaunda family is comforted as we mourn our First President and true African icon."

Another tribute came from Kalusha Bwalya, former captain of the national football team, who said Kaunda had made "an immense impact".