UPDATE 2-CEO of South Africa's troubled Eskom resigns

* Eskom chairman told employees CEO has quit-source

* New CEO to be appointed within 90 days

(Adds background, details)

By James Macharia

JOHANNESBURG, Nov 5 (Reuters) - South African state power firm Eskom's [ESCJ.UL] chief executive Jacob Maroga has resigned, a source close to the company said on Thursday.

Maroga's tenure has been marked by power shortages, a record loss of 9.7 billion rand ($1.25 billion) in the year to March and electricity price rises criticised for stoking inflation as South Africa battles recession. [ID:nLR677617]

The source said Eskom Chairman Bobby Godsell announced the resignation to Eskom staff earlier on Thursday.

An internal Eskom memo, released by the opposition Democratic Alliance, said the resignation was with immediate effect and the board was committed to replace Maroga within 90 days.

The board was considering who to appoint as acting CEO, the memo said. Sources within Eskom have suggested it could be Brian Dames, current head of the generation business.

Maroga has led Eskom in one of its most difficult periods, characterised by a low power reserve margin, rising capital and operating costs and coal procurement problems.

Minister for Public Enterprises Barbara Hogan said earlier that she was trying to resolve a breakdown in relations between the board and Maroga.

She dismissed newspaper reports that President Jacob Zuma had interfered in the matter.

"We are confident that all parties do have the best interests of the country at heart and that they will resolve this matter with the urgency that it deserves," she said.

Maroga denied last week that he was asked to resign by the board. Eskom cancelled a news conference scheduled for 1100 GMT without giving a reason.

The utility has been rationing electricity since early 2008 when the national grid nearly collapsed, forcing mines and smelters to shut and costing Africa's biggest economy billions of dollars.

Eskom has also been widely criticised for fuelling inflation after it was granted a tariff increase of 31.3 percent this year and 27 percent last year, but the state-owned utility says it needs the increases to pay for expansion. [ID:nL1506684]

The utility has asked the energy regulator to raise electricity tariffs by 45 percent annually for three years starting next year, to help Eskom fund the expansion of its generation capacity to meet fast-rising demand. (Additional reporting by Jackie Cowhig in London; Writing by Marius Bosch; Editing by Matthew Tostevin and Keiron Henderson)