(Adds details)

MILAN, June 10 (Reuters) - The board of Atlantia on Thursday accepted the offer from Italian state lender Cassa Depositi e Prestiti (CDP) and partners for the infrastructure group's 88% stake in motorway unit Autostrade per l'Italia.

A large majority of Atlantia's investors last month backed the sale of Autostrade to the CDP-led consortium, paving the way for a deal.

On Thursday, Atlantia's board mandated its CEO and chairman to finalise the agreement, adding completion of the deal could not happen before Nov. 30, but would be no later than June 30, 2022.

CDP, together with Blackstone and Macquarie, tabled their offer in April, valuing Autostrade at 9.3 billion euros ($11 billion).

The proposal is backed by the Italian government, which has been seeking to regain control of Autostrade ever since a bridge run by the toll-road company in the port city of Genoa gave way on Aug. 14, 2018, killing 43 people.

($1 = 0.8220 euros) (Reporting by Francesca Landini Editing by Mark Potter)