Spain's troubled property group Colonial is offering its creditor banks an option to acquire its 15.45% stake in construction group Fomento de Construcciones y Contratas (FCC) as well as its 33% interest in French property firm Societe Fonciere Lyonnaise (SFL). In a statement to the Spanish stock market authorities CNMV, the debt-strapped firm said that it will continue to look for buyers for the stakes despite giving the purchase option to a consortium of creditor banks including Calyon, Eurohypo, Goldman Sachs and the Royal Bank of Scotland. The banks can exercise the buy option from December 11 to January 10.