BERLIN, Dec 21 (Reuters) - Austrian real estate group S Immo (SIAG.VI) said on Tuesday it submitted its previously announced partial offer for up to 10% of the outstanding shares in rival Immofinanz (IMFI.VI) to the takeover commission for examination. The offer comes after the Frankfurt-based real estate company CPI Property Group (O5G.DE), which has already secured 32% in Immofinanz, announced a bid of 21.20 euros per share. As previously announced, S Immo offers 23 euros for each Immofinanz share, Chief Executive Bruno Ettenauer told Reuters in an interview. The partial offer comes sooner than expected as the group had initially applied for an extension until the beginning of January. Reporting by Alexandra Schwarz-Goerlich; Writing by Zuzanna Szymanska, editing by Emma Thomasson