* Atlantia asks for substantial improvement of consortium bid * CDP and partners value 100% of Autostrade at 9.1 bln euros * Sale of stake part of efforts to end political dispute (Recasts with Atlantia’s board decision) MILAN, Feb 26 (Reuters) - Italy’s Atlantia said on Friday an offer by a consortium of investors led by state lender CDP for its 88% stake in Autostrade per l’Italia fell short of the mark and asked its top managers to see if the bid could be sweetened. “The offer falls below expectations,” the Italian infrastructure group said in a statement, adding it had mandated the chief executive and the chairman to assess “the potential for the necessary substantial improvements” to the bid. Italian state lender CDP, together with co-investors Macquarie and Blackstone, has presented a proposal valuing all of Autostrade per l’Italia at 9.1 billion euros ($11 billion). The consortium also requested Atlantia guarantee up to 700 million euros in potential damage claims and another roughly 800 million euros for a pending legal case, making the bid less attractive than previously expected. One source said the consortium estimated overall pending legal claims against Autostrade at 3 billion to 4 billion euros, adding the 700 million euro cap did not mean the amount would be detracted from the offer price from the start. Earlier on Friday Atlantia’s minority investors TCI and Spinecap had called on Atlantia’s board to reject the offer, saying it undervalued the asset. “No deal is better than a bad deal, especially a bad deal and a wrong price,” TCI Advisory Services partner Jonathan Amouyal said in a emailed comment to Reuters. TCI, which holds an indirect stake of around 10% in Atlantia, repeated that the value for 100% of Autostrade should be no less than 12.5 billion euros. The board will hold a further meeting in order to take a final decision on the offer in due time, Atlantia said. The negotiations between Atlantia and the CDP-led consortium are part of an effort to end a political dispute over Autostrade’s motorway concession triggered by the collapse of a motorway bridge run by the unit. The bid expires on March 16, but the deadline could be extended in case Atlantia calls an extraordinary shareholders meeting (EGM) on the issue, according to one source with knowledge of the matter. Shares in the group ended down 0,7%, after recovering some losses, as investors waited for the decision of the board. Atlantia, which is controlled by the Benetton family, owns 88% of Autostrade, with Germany’s Allianz and funds DIF, EDF Invest and China’s Silk Road Fund holding the rest. The group also kept open an alternative plan to demerge and sell its stake in Autostrade per l’Italia unit and called an EGM on March 29 to extend to end-July a deadline for offers for the demerged stake. ($1 = 0.8243 euros)