* Sale or spin-off a condition of planned CA Immo merger
* Net asset value of portfolio 400 mln euros in October
* Shares up more than 3 percent (Adds shares, background, details on portfolio)
VIENNA, March 15 (Reuters) - Immofinanz will invite around 25 "pre-qualified" parties which have expressed an interest to take part in the sale of its portfolio of five shopping centres in Moscow, the Austrian property group said on Wednesday.
Getting rid off the shopping centres, which have weighed on Immofinanz' results, is a precondition for a planned merger with Austrian peer CA Immo, in which Immofinanz already holds a 26 percent stake.
Immofinanz has been offering rent reductions to its Moscow tenants who would otherwise struggle to pay their rent in dollars.
The sale of the properties, which in October had a book value of around 1.1 billion euros ($1.17 billion) including 700 million in debt, will be initiated "shortly", Immofinanz said in a statement.
Shares in Immofinanz were up 3.4 percent at 0920 GMT, hitting a one-month high.
A spokeswoman added that a spin-off remained an option, but that the company preferred a sale. Some smaller shareholders have expressed a preference for a spin-off.
Russia's O1 Group, which sold its 26-percent stake in CA Immo to Immofinanz last year, has expressed interest in the shopping centres.
$1 = 0.9404 euros Reporting by Shadia Nasralla; editing by Jason Neely