(Recasts with source, adds detail)
MILAN, Dec 23 (Reuters) - Italian state lender Cassa Depositi e Prestiti (CDP) has put forward a new, non-binding offer for Atlantia 's ATL.MI toll road unit that implies a lower valuation than an initial offer of 8.5-9.5 billion euros, a source close to the deal said on Wednesday.
The revised offer includes stronger guarantees, the source added, without elaborating.
CDP said earlier in a statement the consortium it leads, which includes Macquarie MQG.AX and Blackstone (NYSE:BX) BX.N , will proceed swiftly with its due diligence of Atlantia's motorway assets but needs further in-depth analysis to be able to present a binding offer.
Italian daily Il Messaggero reported on Wednesday that CDP's new offer valued Atlantia's 88% stake in Autostrade per l'Italia (ASPI) at about 400 million euros less than the first bid.
Infrastructure group Atlantia has said CDP has until July to present an offer, but a government source last week expressed confidence that the two parties will be able to reach a deal by mid-January. deal would put an end to a dispute sparked by the 2018 collapse of a motorway bridge operated by Autostrade in which 43 people died.