South Africa is set to see its most blackouts in history this year with power cuts extending to almost 10 hours a day, affecting businesses and households in an economy already hobbled by high interest rates and inflation.

Charities, business groups and politicians have called on Truss and Sunak to set out how they would help Britons cope with a forecast 82% rise in energy prices in October.

The electricity used to power Australian homes is usually bought and sold across the populous east of the country, a system designed to lower wholesale costs and diversify supply.

The union is protesting against government plans to amend legislation governing the country's power sector, which include removing restrictions on competitive bidding for renewable power projects.