MILAN - U.S. asset manager BlackRock and Qatar's sovereign fund QIA are interested in investing in Atlantia's motorway unit along with Italian state lender Cassa Depositi e Prestiti (CDP), two sources with knowledge of the matter said.

The two could be part of a consortium made of Italian and foreign funds that is expected to buy around 20% in Atlantia's Autostrade per l'Italia once it is demerged from its parent company, the source said.

BlackRock and Qatar Investment Authority declined to comment on the issue.

Autostrade is being sold off after the Italian government forced Atlantia to hand over control of the unit or face being stripped of its lucrative tollway concession in the wake of the deadly collapse of a motorway bridge in 2018 in which 43 people were killed.

The consortium of investors and CDP could buy a controlling stake in Autostrade in an initial public offering to allay concerns over the price of the asset, a source close to the matter said on Sunday.

The preliminary deal reached between Atlantia and the government will likely be ratified by Aug. 3, just before the inauguration of the new bridge in Genoa, the source said.

Australian infrastructure fund Macquarie, U.S. investment firm Blackstone and the insurance arm of Poste Italiane are among the other suitors for Autostrade, sources have told Reuters.

Atlantia, which is controlled by the Benetton family, currently has an 88% stake in Autostrade, with Germany's Allianz, France's EDF and China's Silk Road owning the rest.

(Reporting by Giuseppe Fonte and Stephen Jewkes, writing by Francesca Landini; editing by James Mackenzie) ((james.mackenzie@thomsonreuters.com; +39 02 66129533 ; Reuters Messaging: Reuters Messaging james.mackenzie.reuters.com@reuters.net))