UPDATE 1-Angola's Dos Santos fires energy minister -Angop

* Dos Santos names Joao Batista Borges new minister

* Electricity sector failed to perform (Adds background, details)

By Shrikesh Laxmidas

LISBON, Dec 2 (Reuters) - Angolan President Jose Eduardo dos Santos has sacked Energy Minister Emanuela Vieira Lopes, blaming the disappointing development of the country's electricity sector, state news agency Angop reported on Friday.

Angop said Dos Santos sacked Energy and Water Minister Emanuela Vieira Lopes and replaced him with Joao Batista Borges, a Secretary of State in the energy ministry.

Oil-rich Angola has made substantial investments in the power sector since 2002 to restore an infrastructure destroyed by a 27-year long civil war, but the results have been limited.

The change will not affect the oil sector in Africa's second largest crude producer, which the government administrates through a specific oil ministry.

Dos Santos said the electricity sector's performance in the last two years "has not been satisfactory".

"The results of the second half of this year will be even worse than those in the first half," Dos Santos said.

Analysts say Angola's energy investments have failed so far to translate into widespread electrification, with only an estimated 30 percent of the country's population of around 18 million benefitting from access to power.

Electricity service is unreliable, with consumers and businesses affected by long and regular outages forced to resort to private generators to cope with the intermittent supply.

Angola's power system is seen as fragmented due to the absence of a national transmission backbone.

"The losses of energy produced are very large, the system for distributing and selling energy to consumers is not efficient," Angop cited Dos Santos as saying.

Dos Santos said the new minister's background in electrical engineering should help the sector execute the government's plans "at a very delicate time".

The president said in a state of the nation speech in October that his government plans to invest $17 billion in energy distribution projects by 2016 and that if well executed they will help decrease the energy problems by 2013 and solve them altogether by 2017. (Editing by Marius Bosch)