The memorandum of understanding signed last week will see Inyosi supply coal to Kusile, which is currently under construction in the Mpumalanga province, Eskom said in a statement.

"Eskom and Anglo American are key pillars of the South African economy and we therefore cannot fail the country," Eskom chief executive Tshediso Matona said.

After years of delay, the coal-fired Kusile is expected to be completed next year, one of three power stations Eskom is building to meet rising demand in Africa's most advanced economy.

The first unit of the Medupi power plant is due to be linked to the grid by the end of 2014 and could offer some relief to the troubled electricity system after three power emergencies this year.

Eskom and Inyosi would cement the memorandum with a binding contract once they resolved a deadlock over the power utility's black empowerment requirements, an Anglo American Coal spokesman said.

(Reporting by Zandi Shabalala; Editing by Stella Mapenzauswa)