* Board set to meet at 1600 GMT - sources
* Analysts value 49 pct stake at around 2.5 bln euros (Adds detail, quotes from sources, background)
By Gianluca Semeraro and Lisa Jucca
MILAN, Jan 7 (Reuters) - The board of Generali, Italy's biggest insurer, is to discuss buying the 49 percent of a joint venture with Czech group PPF it does not already own, three sources with knowledge of the situation said.
The proposal to buy the stake, which analysts value at around 2.5 billion euros ($3.3 billion), is the first big boardroom test for chief executive Mario Greco, set to present the result of a review Generali's asset portfolio on Jan. 14.
The sources said on Monday the proposal envisaged Generali buying 25 percent of the fast-growing eastern European joint venture from PPF, controlled by Czech magnate Peter Kellner, with an option to buy the remaining 24 percent late next year.
"The idea is to purchase (the 49 percent stake) in two stages," said one of the sources, on condition of anonymity.
The sources did not disclose financial details. One said the board was due to meet at 1600 GMT on Monday.
Generali and PPF both declined to comment.
Analysts have long said Generali needs to make up its mind on the future of the joint venture with PPF, which itself has an option to sell its 49 percent stake in July to Generali or a third party.
PPF, which has borrowed 2 billion euros using its stake in the joint venture as collateral, could use the proceeds to repay debt and free up funds for further investments.
Greco, who replaced long-standing CEO Giovanni Perissinotto in August with a remit to improve profitability at Generali, is also looking to sell non-core assets such as Swiss-based private bank BSI and a U.S. reinsurance business. ($1 = 0.7634 euro) (Additional reporting by Paola Arosio; Writing by Lisa Jucca; Editing by Dan Lalor)