UPDATE 2-Norway's Entra urges shareholders to reject $4 bln takeover bids

* Swedish firms compete for Norway real estate company

* SBB, Castellum launched rival offers

* Balder holds 20% Entra stake, may block takeover (Adds share price, quotes)

OSLO, Jan 29 (Reuters) - Norwegian real estate firm Entra , subject to a three-way battle for control, on Friday urged its shareholders to reject a set of competing bids for the company, arguing it should remain independent.

Swedish rivals SBB and Castellum are both attempting a takeover, valuing Entra at up to 34.6 billion crowns ($4.0 billion), while a third company, Balder, has amassed a large stake and may block the others.

“The board recommends the Entra shareholders with a long term view on their investment to not accept any of the offers,” said Chairwoman Siri Hatlen, adding that the recommendation was unanimous.

SBB’s cash and stock bid values Entra’s shares at 190 Norwegian crowns each, topping a similar approach by Castellum valued at 186 crowns.

Both suitors require acceptance from 90% of shareholders in order to complete any transaction, which would likely be difficult to obtain, Entra’s board noted.

Balder, which on Jan. 18 said it had raised its ownership to 20% from 5% in early December, has said it did not plan to sell, as has Folketrygdfondet, a state pension fund owning around 11%.

“The Board is strongly committed to continue its work to create further shareholder value in an independent Entra,” Hatlen said.

Entra’s shares have risen by 33% since news of a possible bid emerged on Nov. 24, trading at 191.3 crowns at 1206 GMT on Friday.

Nordic brokers Carnegie have said bids for Entra could eventually reach 200 crowns per share.

The Norwegian government in November sold its 8.24% stake in Entra to Castellum, with the caveat that the price for the state’s shares must be increased if Castellum were to raise its bid. ($1 = 8.6473 Norwegian crowns) (Editing by Gwladys Fouche;Editing by Elaine Hardcastle)