A local publishing group had requested the information,
saying it showed a cosy relationship kept secret from the public in which Eskom
provided electricity at cut-rate prices.
Judge Frans Kgomo said the release was in the public
interest, radio broadcaster Eyewitness News reported.
Eskom spokesperson Hilary Joffe said the company would not appeal the ruling.
BHP could not immediately comment.
The case was brought by Sake24, a division of Naspers [JSE:NPN].
BHP said it would carefully consider the ruling and whether it
would appeal.
Contracts to supply electricity to the mining firm's Mozal
smelter in Mozambique and its Hillside and Bayside smelters in South Africa
accounted for nearly all of Eskom's embedded derivative liabilities, which led
to a book value loss of R9.7bn in the year to end of March 2009.
The contracts, two of which are still valid, have been a thorn in the side for cash-strapped Eskom, already struggling to find the money it needs to build new power stations in Africa's biggest economy to supply fast rising demand.
The deals were agreed to several decades ago when there was
abundant supply in the country as a part of a government policy of underpricing
power to attract industry.
Eskom has since sought to bring power tariffs on par with
their production costs.
The utility was granted an annual increase in tariffs of
around 25% for three years starting in 2010 and it is likely it may be granted
two additional increases along the same lines after that.