Akkerland Boerdery, the owners of two game reserves in Limpopo, told City Press that the Government asked to buy their land but was only willing to offer a tenth of the price.
When the offer was refused, ministers allegedly sent a letter which said: "Notice is hereby given that a terrain inspection will be held on the farms on April 5 2018 at 10am in order to conduct an audit of the assets and a handover of the farm's keys to the state."
AgriSA union spokeswoman Annelize Crosby told the paper: "What makes the Akkerland case unique is that they apparently were not given the opportunity to first dispute the claim in court, as the law requires."
If the land is seized it will be the first time that the South African Government has refused to pay market value for land.
Since the end of apartheid in 1994, the ANC has followed a 'willing seller, willing buyer' process to redistribute white-owned farms to blacks.
But according to a government audit last year, 72 per cent of farmland in South Africa is still owned by whites, despite them making up 9 per cent of the population.
That statistic prompted Cyril Ramaphosa, South Africa's President who succeeded Jacob Zuma last year, to commit to a programme of land expropriation.
His ANC party has promised to 'test out' section 25 of the constitution, which allows the Government to seize land to re-balance past racially discriminatory laws.
The constitution makes it clear that reasonable compensation must be offered to the owner of the land, but the ANC is now planning a number of test cases to see if land can be seized without money changing hands if it is "in the public interest".
If such bids fail, the ANC has threatened to amend the constitution.
A programme of land seizures in nearby Zimbabwe in the 1990s sent the country into an economic spiral from which it has never fully recovered.
Reports this month suggested ministers have already drawn up a list of 139 South African farms to be targeted, though the Government denies the existence of any such list.
Omri van Zyl, head of the Agri SA union, which represents mainly white commercial farmers, told the Express: "The mood among our members is very solemn.
"They are confused about the lack of any apparent strategy from the government and many are panicking.
"So many farms are up for sale, more than we've ever had, but no one is buying."
ANC chairman Gwede Mantashe sparked more panic last week when he suggested that anyone owning more than 10,117ha would be targeted.
Agri SA said about 20 per cent of South Africa's farms produce 80 per cent of the food, and many of those properties would be affected by the cap.
There are fears that the release of the list of 139 farms to be seized has already made the land worthless.
Cattle farmer Jo-an Engelbrecht told the ABC's Foreign Correspondent his farm just outside Johannesburg was now "worth zero".
"We had several auctions in the last two or three weeks cancelled because there was no people interested in buying the land," he said.
"Why would you buy a farm to know the Government's going to take it?"
