IFM GIF, a long-time investor, said on Monday it would offer 33 euros ($34.51) per share but added that it was not seeking a majority and that it did not expect the City of Vienna, the province of Lower Austria or the Employee Trust to sell their share.

The Austrian capital and the adjoining province hold 20% each, employees hold another 10% of Vienna Airport's 84 million shares.

"Despite the difficult economic situation for the aviation industry, we believe in the strong fundamentals of Flughafen Wien and in Austria as a place to invest," IFM Investors executive director infrastructure, Werner Kerschl, said.

Vienna Airport shares soared as much as 25% but at 32,80 euros they remained below the offer price.

A spokesperson for the airport operator said the group would comment on the offer in the coming weeks.

($1 = 0.9562 euros)

(Reporting by Kirsti Knolle, editing by Thomas Escritt)