A stifling heatwave that has swept parts of South Africa in recent weeks has killed eight people over several days, the government said Tuesday.

The dead were mostly farm workers in the sparsely populated and largely semi-arid Northern Cape province which borders Namibia and Botswana, according to the labour ministry.

"We are concerned about the impact of the hot weather parts of South Africa has been experiencing," government spokesman Michael Currin said in a statement.

"We are extremely sad to hear about the passing of eight people that have died of heat stroke in the Northern Cape after a heatwave hit the province over the week," he added.

Parts of South Africa have been scorched by a summer heatwave with temperatures hitting 40 degrees Celsius on some days.

The European Union's climate monitoring service said earlier this month that the last eight years were the warmest on record globally.