UPDATE 1-Italy state fund to bid for AnsaldoEnergia stake

(Add details on proposed offer, quote, background)

ROME, Oct 12 (Reuters) - Fondo Strategico Italiano and a group Italian investors plan to make an offer for a "significant" minority stake in Finmeccanica power engineering unit AnsaldoEnergia, the state-backed fund said in a statement on Friday.

State-owned Finmeccanica has put on the block its 55 percent AnsaldoEnergia stake and its transportation businesses as part of a vital turnaround of Italy's No.2 industrial group.

"FSI and the industrial investors intend to formalise a joint, non-binding manifestation of interest and verify with Finmeccanica if conditions are there to reach an agreement soon," FSI said in the statement.

A spokesman for Finmeccanica had no immediate comment.

Talk of an offer from FSI emerged earlier in October after Siemens , Europe's biggest engineering group, emerged as the favourite to buy AnsaldoEnergia with a bid estimated at 1.3 billion euros.

Prospects of a sale to the German group raised protests by trade unions and politicians, who called for AnsaldoEnergia, which employs about 3,000 people, to remain in Italian hands.

U.S. fund First Reserve owns the remaining 45 percent.

The sale of AnsaldoEnergia could become the first major disposal for Finmeccanica Chairman Giuseppe Orsi, who is under pressure from a corruption probe and has promised to sell assets worth 1 billion euros by the end of the year.

FSI, which is controlled by state holding company Cassa Depositi e Prestiti, and the Italian groups said they had signed a memorandum of understanding for an offer.

The Italian investors are Gruppo Energia Brescia, Gruppo Acciaierie Venete and entrepreneur Davide Usberti, who controls gas company GasPlus .

(Reporting by Naomi O'Leary and Danilo Masoni; Editing by Bernard Orr)

((naomi.oleary@thomsonreuters.com)(+39 06 8522 4392)(Reuters Messaging: naomi.oleary.reuters.com@reuters.net))