ROME (Reuters) - Italy's state holding company CDP [CDP.UL] and Intesa Sanpaolo (ISP.MI) have signed a non-binding agreement to join ArcelorMittal's (MT.AS) bid to buy Italian steelmaker Ilva, a source close to the matter said on Friday.

The involvement of CDP and Intesa, which the source said would amount to about 100 million euros ($118 million), would replace the share in the consortium currently held by Italian steel processor Marcegaglia.

EU antitrust authorities in November upgraded their investigation into whether the proposed purchase of Ilva by the consortium led by ArcelorMittal, the world's biggest steelmaker, would lead to steel price hikes.

The exit of Marcegaglia from the deal could make it easier to overcome the antitrust concerns.

Earlier Italy's industry minister, Carlo Calenda, held talks with ArcelorMittal Europe CEO Aditya Mittal.

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(Reporting by Francesca Piscionieri; writing by Philip Pullella; editing by Alexander Smith)