Goodwill Zwelithini, the controversial but revered king of South Africa's Zulus, died Friday aged 72 after weeks in hospital, his palace announced.

Zulu King Goodwill Zwelithini greets his supporters at The Moses Mabhida Football Stadium in Durban on October 7, 2018, during Umkhosi Welembe, an annual commemoration of Zulu King Shaka ka Senzangakhona, a revered military strategist who united the tribes to form the Zulu Nation. (File photo: AFP)

The king wielded great influence among millions of Zulus through his largely ceremonial and spiritual role despite having no official power in modern South Africa.

"It is with the utmost grief that I inform the nation of the passing of His Majesty King Goodwill Zwelithini ... King of the Zulu nation," the palace said a statement signed by Mangosuthu Buthelezi, a powerful veteran politician who is also a Zulu prince.

The king was admitted to hospital last month for diabetes.

"Tragically, while still in hospital, His Majesty’s health took a turn for the worse and he subsequently passed away in the early hours of this morning," the statement said.

Born in Nongoma, a small town in the south-eastern Kwa-Zulu Natal province, Zwelithini ascended the throne in 1971 during the apartheid era at the age of 23, three years after the death of his father.