US President Donald Trump's tariffs on South Africa could cause around 100 000 job losses, with the agriculture and automotive sectors hardest-hit, central bank governor Lesetja Kganyago said on Wednesday.

Kganyago told local radio station 702 that the impact of the 30% tariff, which Africa's biggest economy faces from August 1, could cause significant damage to specific industries.

"The impact in agriculture could actually be quite devastating because agriculture employs a lot of low-skilled workers, and here the impact is on citrus fruit, table grapes and wines," Kganyago said.

He said statistics showing South African car exports to the United States slumped more than 80% in the wake of import tariffs imposed on cars by the Trump administration in April were very concerning.

"If we do not find alternative measures the impact on jobs could be around 100 000, so that is what we actually face," the governor said.

South Africa already has one of the highest unemployment rates in the world, with the official rate sitting at 32.9% in the first quarter of this year and an expanded definition at 43.1%.

Farmer groups have also warned of the adverse impact of the tariffs on producers of citrus, macadamia nuts, grapes, wine, fruit juices and ostrich leather.

In the citrus sector alone the tariffs have put 35 000 jobs in jeopardy and threaten to devastate towns such as Citrusdal in the Western Cape that are heavily dependent on exports to the US.