ROME, March 6 (Reuters) - ArcelorMittal and Italy's Marcegaglia have made an offer to buy Italy's beleaguered Ilva steel plant, promising to invest 2.3 billion euros ($2.4 billion) and boost production, ArcelorMittal said on Monday.
Italy took over the loss-making Ilva plant, Europe's largest by capacity, in 2015 to save thousands of jobs and clean up the polluted site in the southern Italian city of Taranto.
Large portions of the factory were sequestered by magistrates in 2013 on accusations that owners were responsible for an environmental disaster.
A rival offer by a consortium that includes India's JSW Steel and state holding company lender Cassa Depositi e Prestiti is expected to be announced later on Monday.
The government is expected to say which offer it will accept in about a month's time.
The government wants a buyer that will restore the factory's fortunes by cleaning it up and investing to make it economically viable in a region with soaring unemployment.
Intesa Sanpaolo, Italy's biggest retail bank, signed a letter of intent along with ArcelorMittal, the world's largest steelmaker, and Marcegaglia, a family-run steel processing group. The value of the offer was not given.
The consortium said it would boost output with low-carbon steel-making technologies, ultimately up to 9.5 million tonnes of finished products from less than 6 million tonnes now. It also said it would create a research and development centre with an initial investment of 10 million euros.
"It has been sad to watch the decline of this great company in recent years and we are excited to have the chance to contribute to a new renaissance of this Italian steel icon," Marcegaglia's chairman and chief executive, Antonio Marcegaglia, said in a statement. ($1 = 0.9436 euros) (Reporting by Steve Scherer, editing by David Evans)