(Adds Eskom CEO)

CAPE TOWN, Sept 18 (Reuters) - South African power utility Eskom implemented Stage 6 power cuts early on Sunday morning, its worst level touched for the second time this year although a "total blackout" was not imminent, its chief executive officer said.

The last time Eskom resorted to Stage 6, which means at least six hours without power a day for most South Africans, was in June. It had previously done so during a power crisis in December 2019.

The cash-strapped utility has been struggling to keep the lights on in Africa's most industrialised economy as regular power cuts curb economic growth and fuels public frustration as Eskom seeks a new 32% tariff hike.

"We are doing our level best to avoid a total system collapse ... and total blackout," CEO Andre de Ruyter told a media briefing.

"That is not an imminent risk," he added.

Eskom, which gets most of its electricity from ageing coal-fired power plants prone to breakdowns, plans to cut about 6,000 megawatts (MW) of power in a staggered manner to prevent a catastrophic collapse of the national electricity grid.

Currently there were unplanned load losses of 15,630 MW, about a third of Eskom's total nominal capacity of just over 45,000 MW.

The utility earlier appealed to the public to help conserve electricity as it moved to its highest level of power cuts, only the third time since Eskom started what it calls "loadshedding" following a chronic power crisis that started more than a decade ago.

After an urgent board meeting on Saturday, Eskom intends going to the market on Monday to procure an extra 1,000 MW from independent power producers, although it was unclear when this would become available, De Ruyter said.

On Saturday, when the utility ratcheted up loadshedding to Stage 5 after five generating units broke down, Eskom said its emergency generation reserves had been depleted by extensive use to limit the amount of power cuts over the past two weeks.

"Our chief financial officer has made available an additional 500 million rand to purchase more diesel," De Ruyter said after Eskom burned through 7.7 billion rand ($438 million) of diesel in the past five months of the financial year.

($1 = 17.5988 rand) (Reporting by Wendell Roelf; Editing by Christian Schmollinger, William Mallard and David Evans)