"We are with Arcelor Mittal, which is the best partner for a complicated turnaround like Ilva," Emma Marcegaglia said on the sidelines of an event in Milan.

She said the offer would be made before the end of May, adding the bidders had asked Italian state lender Cassa Depositi e Prestiti to join in.

A spokesman for Arcelor Mittal declined to comment.

Last year, the Italian state took over administration of loss-making Ilva.

(Reporting by Gianluca Semeraro, additional reporting by Steve Scherer, writing by Isla Binnie)