Eni close to hiring adviser to sell Mozambique gas stake - sources

* Sale of 15 pct stake could raise up to $5 bln - sources

* Interest from players in Asia - sources

* Eni CEO has already spoken of selling down stake further (Adds source comments, background)

By Sophie Sassard and Stephen Jewkes

LONDON/MILAN, March 27 (Reuters) - Eni (NYSE: E - news) is close to mandating a bank to sell a stake of up to 15 percent in its giant gas field in Mozambique which could raise as much as $5 billion for the Italian oil and gas major, banking sources said.

Eni sold 20 percent of its Mozambique offshore gas acreage to Chinese oil company CNPC last year in a deal worth around $4.2 billion.

The Italian state-controlled major still has a 50 percent stake in its biggest ever gas discovery - known as Area 4 - and Chief Executive Paolo Scaroni has previously talked about selling down further.

"Eni has mandated a bank to sell a 15 percent stake in its Mozambique gas field in a possible $5 billion deal. A lot of players, especially from Asia, are expected to show up," one of the sources said.

Another source said top Chinese offshore oil and gas producer CNOOC Ltd (HKSE: 0883.HK - news) was high up on the list of potential buyers because it was keen to build up a liquefied natural gas (LNG) business.

Sources have previously told Reuters other oil majors such as ExxonMobil, Chevron (Amsterdam: CHTEX.AS - news) , Shell (LSE: RDSB.L - news) and Total (Brussels: FP.BR - news) could be interested in Eni's block. But a deal with these larger companies might threaten Eni's control of a project that is crucial to its future.

A sector expert also said that it had become more difficult for oil and gas majors to justify large upstream investments with their investment committees because the focus is on improving the performance of existing assets rather than expanding capacity.

Eni declined to comment.

Eni's acreage in Mozambique is thought to contain resources of more than 85 trillion cubic feet (tcf) of gas. It is part of the wider Rovuma basin that holds more than 150 tcf, enough to supply Germany, Britain, France and Italy for 15 years.

Cash from the sale could help fund investments by Eni in the area estimated at around $50 billion.

"A 15 percent stake would be worth around the same, pre-tax, as the 20 percent stake sold to the Chinese last year," a third banking source said.

Some analysts told Reuters last year the Chinese offer for the 20 percent stake had been below their value estimates.

In February Scaroni said Eni could reduce its stake in Area 4 to 35 percent. "We are looking for a potential partner who is also a buyer of gas, possibly in the region," he said.

Scaroni's third mandate at the helm of Eni expires in around a month's time and some government and industry sources say he might not be reappointed as the new government of Matteo Renzi seeks fresh faces to head state-controlled groups.

(Reporting by Sophie Sassard and Stephen Jewkes; Editing by Pravin Char)