WARSAW, Nov 14 (Reuters) - Polish state-controlled real estate group PHN PHN.WA is preparing for due diligence ahead of the government's sale of another stake in the company to an investor, PHN said on Thursday. Poland, which owns almost 73 percent of PHN, already sold a 25-percent stake in a 239 million zloty flotation at the beginning of the year and said it would look for a strategic partner for PHN after the initial public offering. ID:nW8N0B400C "The company is in preparations for the due diligence process, which includes preparing documents accessible for the potential investors," PHN said in a statement. Sources told Reuters last month that Poland may need to delay the transaction to update the value of PHN's assets, threatening the government's 5-billion-zloty privatisation revenue target for this year. ID:nL6N0HS1S7 PHN, created by the combination of several state property holdings, owns 150 real estate assets, including Warsaw's oldest skyscraper and villas rented by foreign embassies in the city's up-market Wilanow district. Shares in PHN were flat at 0911 GMT at 26.60 zlotys, valuing the whole company at 1.18 billion zlotys ($377 million). ($1 = 3.1312 Polish zlotys) (Reporting by Agnieszka Barteczko; editing by Tom Pfeiffer) ((agnieszka.barteczko@thomsonreuters.com)(+48226539721)(Reuters Messaging: agnieszka.barteczko.reuters.com@thomsonreuters.net)) Keywords: POLAND PHN/