South Africa's former deputy president, David Mabuza, who helped bring current President Cyril Ramaphosa to power, has died, the presidency said on Thursday.

Mabuza, 64, served as deputy president from 2018 to 2023 and played a key role in ensuring Ramaphosa won the tight 2017 party contest to lead the African National Congress. Details on the cause of death were not immediately available.

In the months after the 2017 contest, Ramaphosa's allies on the ANC executive pressured scandal-plagued Jacob Zuma to quit, paving the way for Ramaphosa to become head of state.

"The former deputy president deserves our appreciation for his deep commitment to the liberation struggle and to the nation's development as an inclusive, prosperous, democratic state," Ramaphosa's office said in a statement.

Mabuza had not been seen much in public recently and had been unwell, public broadcaster the South African Broadcasting Corporation reported, without disclosing the illness.

A former schoolteacher and premier of the Mpumalanga province, Mabuza struggled to shrug off allegations - which he denied - of irregular tenders for a 2010 World Cup stadium and links to political killings.

Mabuza told the media that he had been poisoned in 2015, dubbing himself "The Cat" for surviving what he described as political attacks, according to SABC.

The moniker stuck, and it later emerged that Mabuza had travelled to Moscow for specialised treatment.