(Changes amount Petrobras paid for Libra stake to 6 billionreais from $7 billion in paragraph 8)
* Petrobras plans to reduce its 40 pct stake in Libra field
* Sale could fetch up to $1.5 bln -analysts
By Ron Bousso and Jeb Blount
LONDON/RIO DE JANEIRO, Dec 9 (Reuters) - Brazil's state-runoil company Petrobras is offering up to a quarter ofits 40 percent stake in the huge Libra offshore oil prospect asits seeks to reduce the largest debt in the global oil industry,two industry sources said on Tuesday.
The stake could fetch up to $1.5 billion, according toanalysts at Macquarie, and is likely to attract internationaloil companies keen to expand in one of the world'sfastest-developing oil basins.
Petroleo Brasileiro SA, as Petrobras is formally known, istargeting $15.1 billion in disposals by the end of next year buthas struggled to sell assets in less attractive prospects offBrazil and in the Gulf of Mexico.
Chief Executive Aldemir Bendine has told Brazil's congressthat the company will not be able to meet repayment obligationson its debt of more than $130 billion and maintain a $19 billioninvestment plan next year unless it hits the disposal target.
The company is now offering sought-after oil prospects inthe so-called sub-salt areas in the Santos basin south of Rio deJaneiro, several industry sources said. These areas contain vastreserves trapped deep beneath the sea bed by a layer of mineralsalts.
Petrobras did not respond immediately to a request forcomment.
"Petrobras finally realised the assets they were offeringwere not as attractive as they thought and has decided to offeropportunities that are more likely to fetch a higher price," anindustry source said.
In 2013 Petrobras made an upfront payment of 6 billion reaisfor its 40 percent stake in the Libra development, which wasBrazil's first offshore oil lease sold under production-sharingagreements under which the company is required to be theoperator and hold a minimum 30 percent stake.
Royal Dutch Shell, which would become the biggestforeign investor in Brazil after the completion of its proposed$70 billion merger with BG Group, and France's Total each hold a 20 percent stake in Libra. China NationalPetroleum Corp and China's CNOOC each hold10 percent.
First oil from the Libra field is expected to flow in thefirst quarter of 2017. The government estimates that Libra hasbetween 8 billion and 12 billion recoverable barrels of oil andgas equivalent.
Analysts at Macquarie, who have an underperform valuation onPetrobras, cautioned over its ability to keep to its asset salesplans.
"We maintain our concerns regarding the Petrobras' abilityto deliver its short-term ($15.1 billion) and medium-term ($42.6billion) divestment plan," they said. (Editing by David Goodman)