A sale of the "Book House" in the heart of Helsinki, together with a long-planned property sale in St Petersburg, would help the indebted company which posted a core quarterly loss for the third quarter.

"Values in Helsinki are record high at the moment, and as we don't practise retail business in this property any longer, we will start investigating a possible divestment," said Bjorn Teir, director for real estate at Stockmann.

Teir did not give a book value for the Book House, designed by architect Alvar Aalto and built in 1969. Analyst Sauli Vilen from research firm Inderes gave a rough estimate of around 100 million euros (£88.94 million).

Stockmann used to sell books there itself but sold that business to Sweden's Bonnier in 2015.

Shares in Stockmann, which fell about 40 percent last year, were up 7.7 percent at 4.685 euros by 1325 GMT.

The company has struggled in recent years due to economic slowdowns in Finland and Russia as well as the rise on online shopping. Its interest-bearing liabilities at the end of September were 843 million euros, or about 95 percent of equity.

Stockmann has been negotiating with investment company O1 Group over the sale of its St Petersburg department store property, which has a book value of 181 million euros. That process continues, it added.

In November, the company put its real estate assets including the Book House forward as collateral for a new refinancing package.

The total fair value of its real estate assets is 950 million euros, the majority of which is estimated to be made up of the company's Helsinki flagship department store.

Stockmann cut its profit outlook in September and Vilen said it could do so again ahead of its 2017 results due on Feb. 14.

The company has forecast full-year comparable core operating profit to be in line or slightly down from 2016. In the first nine months of the year, the loss widened to 12 million euros from 4 million a year earlier.

"The fact that no new warning has been given yet means their Christmas sales have been rather good. But Stockmann was far from the guidance after nine months so a mild warning is still likely," said Vilen, who has a "buy" rating on the stock.

(Reporting by Jussi Rosendahl; Editing by Keith Weir and Mark Potter)