* Decision comes after losing Norway spectrum auction
* Says options include sale of unit (Adds detail, background)
STOCKHOLM, March 5 Sweden's Tele2 has hired investment bank ABG Sundal Collier to review its options in Norway, including selling its operations there, after it lost a December auction for a mobile spectrum key for the development of its Norwegian network.
Tele2, which is Norway's third-largest mobile operator behind Telenor and Teliasonera, has spent almost 400 million euros ($549.70 million) since 2011 to build a business that now has 1.2 million customers and some 1,700 mobile towers.
But it was dealt a blow after Access Industries, a holding company owned by Ukrainian-American billionaire Len Blavatnik who also owns Warner Music Group, won an auction with a $115 million bid for airwaves in the 800, 900 and 1800 megahertz bands.
"As previously communicated we are evaluating our different opportunities for our Norwegian businesses. Exploring various strategic options is an on-going part of our responsibility towards our shareholders," Mats Granryd, CEO and president of Tele2, said in a statement, declining to comment on specific outcomes.
Sources told Reuters in February that Tele2 and Access Industries were in talks, with options including Access selling its spectrum to Tele2, Access buying Tele2's Norway operation, or a licensing of the spectrum to Tele2.
Access would only sell its spectrum to Tele2 on condition that it also buys ice.net, a small Norwegian mobile broadband company owned by Access. Nor is Access willing to pay a high price for Tele2's Norway unit, sources said then.
Tele2's Norway business is worth less than it would be if it had a robust spectrum portfolio because it means renting capacity on rival networks, dampening profit margins.
Tele2 is also looking at other options, such as buying spectrum in the next auction, but it is not certain that the government will sell any this year or next.
Tele2 could also seek an agreement to put its mobile traffic on Telenor or Teliasonera's networks, analysts have said, although this would result in a less profitable business. It was unclear if such talks were underway. ($1 = 0.7277 euros) (Writing by Alistair Scrutton; Editing by Louise Heavens)