South Africa's parliament has approved a bill allowing state expropriations of land to redress racial disparities in land ownership.

The bill, approved on Thursday but in the works since 2008, will enable the state to pay for land at a value determined by a government adjudicator and then expropriate it for the "public interest", ending the willing-buyer, willing-seller approach to land reform.

Most of South Africa's land remains in white hands and many commercial and small-scale farmers are currently facing tough times because of the worst drought in at least a century.

Experts say it will not signal the kind of often violent land grabs that took place in neighbouring Zimbabwe, where white-owned farms were seized by the government for redistribution to landless blacks.

The ruling African National Congress (ANC) said the bill, criticised by some opposition parties and farming groups, would tackle injustices imposed during white-minority rule.

"The passing of the bill by parliament is historic and heralds a new era of intensified land distribution programme to bring long-awaited justice to the dispossessed majority of South Africans," the ANC said in a statement.

Some economists and farming groups have said the measure could hit investment and production at a time when South Africa is emerging from drought - pointing to the serious economic damage arising from farm seizures in Zimbabwe.

They have also complained about a lack of clarity on how it will all work.

The ANC says land will only be expropriated after "just and equitable" compensation has been paid.

Around eight-million hectares (20-million acres) of land have been transferred to black owners since apartheid, equal to eight to 10 percent of the land in white hands in 1994.

The total is only a third of the 30 percent targeted by the ANC.

The national assembly initially passed the bill in February before it was sent for amendments and it remains only for President Jacob Zuma to sign it into law.