* Mandatory takeover bid after buying creditor banks stake
* Risanamento founder Zunino involved in bid
* Deal valued at around 250 mln euros - report
MILAN, Feb 20 (Reuters) - U.S.-based investment fund Colony Capital and the founder of Risanamento have offered to buy stakes in the loss-making Italian property company from creditor banks.
Risanamento said on Thursday that a vehicle called OUI, 70 percent owned by Colony, had told its shareholders it was interested in buying Risanamento shares owned by the banks.
Risanamento was the biggest Italian real estate casualty of a credit crunch in 2009 when falling property prices and the end of easy lending made its large debts hard to sustain.
The company escaped bankruptcy when a court made Intesa Sanpaolo and UniCredit its biggest shareholders, leaving founder Luigi Zunino with a minority stake.
The banks, which also include Banco Popolare, Banca Popolare di Milano and Monte Paschi di Siena , hold an overall stake of around 63 percent. Intesa is the most exposed, with a 36 percent holding.
OUI, 30 percent owned by Zunino, would launch a mandatory bid for all outstanding shares after buying the stake held by Zunino's Sistema Holding.
Risanamento did not disclose the price of any such offer.
Earlier on Thursday Italian newspaper Il Sole 24 Ore said U.S. businessman Tom Barrack, the founder and head of Colony Capital, was ready to launch a bid for Risanamento worth around 250 million euros ($343.8 million).
Barrack would pay 0.2 euros per share to Risanamento shareholders on top of 60 million euros to creditor banks, valuing the overall offer price at 0.28 euros a share, the paper said.
At 1225 GMT Risanamento shares were up 10 percent at 0.23 euros.