Four major cities in South Africa have suffered power cuts due to a huge loss in output after a coal storage silo collapsed.

Blackouts on Sunday were reported in Johannesburg, South Africa's economic capital, Pretoria, Port Elizabeth, and Cape Town, and could run through the whole week, the state-owned power supplier Eskom said.

Eskom lost 1,800 megawatts due to a loss of capacity at its Majuba power station in Mpumalanga in northern South Africa.

A crack in a silo that held more than 10,000 tonnes of coal on Saturday caused the loss, Eskom said, warning of blackouts between 8am and 10pm.

Tshediso Matona, CEO of Eskom, said the incident would exacerbate an already "tight system". 

"An investigation is already under way into the cause of the incident, but it appears that this is an isolated incident specific to the coal infrastructure at Majuba."

South Africans with access to the internet took to social media to express their outrage with the outages.

Eskom has also called on residential users to turn off geysers and pool pumps until 10pm, and switch off non-essential lighting.

It feared that if there are any other supply interruptions, there could be widespread blackouts with a heavy cost to the economy, local media said.

Eskom, which supplies 95 percent of South Africa's electricity, has been struggling to meet growing demand, hobbled by years of underinvestment and ageing infrastructure.

In September, Russia signed a nuclear agreement with South Africa, in a deal to construct eight nuclear reactors at a cost of up to $50bn, to increase its nuclear power generation capacity.

At the time, Minister of Energy Tina Joemat-Pettersson said South Africa sees nuclear power as "an important driver for the national economic growth".

"I am sure that cooperation with Russia will allow us to implement our ambitious plans for the creation by 2030 of 9.6 GW of new nuclear capacities based on modern and safe technologies," she said in a statement.

Here is Eskom's full statement below: 

Source: Al Jazeera and agencies