South African President Cyril Ramaphosa has warned that land grabs would not be tolerated as the ruling African National Congress (ANC) moves to change the Constitution to expropriate property without compensation.

Land remains an emotive issue in South Africa and most of it remains in white hands over two decades after apartheid's demise, despite government programmes aimed at redistribution to narrow glaring racial disparities in ownership.

Clashes over land

Earlier this week, takeovers of vacant land in a suburb between Johannesburg and Pretoria provoked clashes with police.

Speaking to the media in televised remarks near Pretoria after spending the day on a voter registration drive, Ramaphosa was asked about land invasions and the subsequent clashes with police.

"We should not tolerate disorder and lawlessness of that type. Nobody has any right to invade land, to violate other people's rights," Ramaphosa said on Sunday.

"All those who want to invade land - they will get to know that we will not allow that."

Markets spooked

Gauteng Premier David Makhura said those who invade land were not local homeless or landless people; and that the invasions appeared to be "organised".

The ANC's proposal to change the Constitution to allow the government to expropriate land without payment has spooked markets and evoked the takeovers of white-owned farms in neighbouring Zimbabwe.

But Ramaphosa has been at pains to say such a policy in South Africa would be done lawfully and in a manner that did not threaten the economy or food security.

Ramaphosa replaced Jacob Zuma last month as president, after Zuma, whose administration was marred by scandal and missteps, was forced from office by the ANC.

Earlier on Sunday, local media quoted Ramaphosa as telling a church service that: "We are now in healing mode. God is addressing our problems, he is addressing our challenges."