* CDP-led consortium readies offer for 88% of Atlantia’s unit * Minority investor TCI says unit’s value more than 12 bln euros (Adds details on consortium’s offer, Atlantia’s board) MILAN, Feb 23 (Reuters) - A consortium of investors led by Italian state lender Cassa Depositi e Prestiti (CDP) is expected to approve a binding offer for Atlantia’s 88% stake in motorway unit Autostrade per l’Italia later on Tuesday, two sources close to the matter said. The bid will be based on a valuation of 9 billion euros ($11 billion) for 100% of Autostrade, the sources said. A previous non-binding proposal in December was pitched at an 8 billion-euro valuation, one of the sources said. “The offer has been improved since December and is based on a value for the whole of Autostrade of 9 billion euros,” one of the sources said. Barring last-minute surprises, the offer is not likely to include conditions protecting the buyers from the legal risks linked to the deadly collapse in 2018 of a bridge run by Autostrade, one of the sources said. CDP and its investment fund partners Macquarie and Blackstone declined to comment. The consortium and infrastructure group Atlantia have been in talks over the sale of the Autostrade stake since last year. The negotiations are part of an effort to end a political dispute over Autostrade’s motorway concession triggered by the bridge disaster, which killed 43 people on Aug. 14, 2018. The offer is expected to be sent to Atlantia on Wednesday, a third source said, adding that CDP will hold the 51% of the vehicle that will acquire the stake. Atlantia, which is controlled by the Benetton family, will hold a board meeting on Friday to assess the offer and could decide to call a shareholders’ meeting to vote on the proposal if it deems it interesting. As an alternative, Atlantia’s board may reject it and press on with a plan to demerge the motorway unit from the group, betting on a better offer in the coming months. Minority investors in Atlantia, including hedge fund TCI, have criticized the involvement of CDP in the sale of the unit, adding the value of Autostrade is more than 12 billion euros. A government change in Italy, with a new cross-party ruling coalition headed by former European Central Bank Chief Mario Draghi, could also have an impact on the strategy of state lender CDP and its plans for Autostrade. ($1 = 0.8226 euro) (Reporting by Francesca Landini and Giuseppe Fonte in Milan Additional reporting by Stephen Jewkes in Milan Editing by Mark Potter and Matthew Lewis)