OSLO, Dec 7 (Reuters) - Swedish real estate firm Balder has bought a 5% stake in Norway's Entra but has no plans to join the ongoing takeover battle for the Oslo-listed firm, it said on Monday.

Two other Swedish real estate firms, SBB and Castellum, are both bidding for Entra, Norway's largest listed real estate company. (Reporting by Terje Solsvik, editing by Gwladys Fouche)