* Strabag, YIT make non-binding offers
* Hochtief says efforts to sell the unit are ongoing
* Bilfinger says still looking at the unit
* Report in March said ISS, Vinci, Cofely also interested (Recasts, adds comments by Hochtief, Bilfinger)
VIENNA/HELSINKI, May 23 Austrian construction group Strabag and Finland's YIT have both submitted preliminary offers for the services division of Hochtief as the German builder sheds assets in a strategic shift.
Hochtief, controlled by Spain's ACS, has already agreed to sell its airports businesses as part of plans to reduce debt and concentrate on infrastructure.
YIT said it if reached a deal it would make the Hochtief unit part of its building services business Caverion, which it plans to spin off and list later this year.
A Strabag spokeswoman said: "The seller will now examine the offers made and will grant access to the data room to those parties interested, who will be considered as serious bidders."
Hochtief declined to comment on whether it had received any bids for the business, saying only that efforts to sell it were ongoing.
The business has more than 5,000 employees and offers facility and energy management services. For example, it maintains two wind tunnels for premium carmaker Mercedes-Benz and handles heating, air-conditioning and other technical building systems at some offices of ExxonMobil .
The sale of the services business is expected to attract more bids. Hochtief's German rival Bilfinger said on Thursday it was continuing to look at it but declined to comment on whether it was bidding.
A German magazine had reported in March that Denmark's ISS and Vinci and Cofely of France were also interested in the business, which it said Hochtief hoped to sell for as much as 170 million euros ($219 million).
Vinci and Cofely, owned by GDF Suez, declined to comment. ISS was not immediately available for comment.
Earlier this month, Hochtief, based in Essen in Germany, agreed the sale of its airports division for 1.1 billion euros.
($1 = 0.7766 euros) (Reporting by Terhi Kinnunen and Michael Shields; Additional reporting by Matthias Inverardi, Sabine Wollrab, Mette Fraende, Elena Berton and Geert De Clercq; Writing by Maria Sheahan; Editing by Balazs Koranyi and Jane Merriman)