* De Ruyter to start Eskom role next year

* The new CEO is moving from packaging firm Nampak

* Analysts say de Ruyter a surprise appointment

* Eskom battling with high debt, old power plants (Adds analysts, more details)

By Olivia Kumwenda-Mtambo

JOHANNESBURG, Nov 18 (Reuters) - South Africa's government has appointed packaging firm chief executive Andre de Ruyter as the new head of Eskom and tasked him with restructuring the heavily indebted state utility whose power plants are struggling to keep the nation's lights on.

Investor worries about South Africa's economy have been reignited after repeated power cuts in February and March dragged growth into negative territory in the first quarter.

The Ministry of Public Enterprises said de Ruyter, chief executive of Nampak, would start at Eskom on Jan. 15 with the job of splitting the utility into three separate units, under a plan approved by President Cyril Ramaphosa.

De Ruyter spent more than 20 years with petrochemicals group Sasol in several senior roles, which the ministry said gave him global exposure in the energy and chemicals industries.

But some analysts questioned whether de Ruyter, who has been leading a firm that specialises in designing and making packaging, had enough experience in the power business.

"He is a surprise appointment ... It is unclear he has the requisite experience," said Peter Attard Montalto, head of capital markets research at Intellidex. "Nampak is a totally different kettle of fish and has not been clearly successful."

The government has said it would split Eskom into generation, transmission and distribution businesses to boost efficiency, although it has not said how this would achieved without first resolving its huge debt and loss-making problems.

Robust economic growth in South Africa hinges on saving Eskom, which is buried under 440 billion rand ($30 billion) of mountain of debts and provide the nation with enough electricity from its creaking fleet of coal-fried plants.

The government has pledged to give Eskom more than 100 billion rand over the next two fiscal years, with additional aid spread over the next decade.

Eskom's previous CEO, Phakamani Hadebe, resigned this year, citing health reasons. He was the 10th chief executive in a decade to quit a company which has seen a steady stream of departing senior executives and board members.

Chris Yelland, a Johannesburg-based energy expert, said de Ruyter had an "an unenviable task".

"I am not sure if this the right appointment. It's wait-and-see at the moment, but I am filled with a kind of foreboding," said Yelland.

Public Enterprises Minister Pravin Gordhan thanked de Ruyter in a statement "for not only accepting this position at a difficult time for Eskom, but, given Eskom's current financial situation, also agreeing to a lower compensation package than the position currently pays."

($1 = 14.7742 rand) (Additional reporting by Mfuneko Toyana; Editing by James Drummond and Edmund Blair)