(Adds more details) MILAN, Jan 19 (Reuters) - Talks between...

(Adds more details)

MILAN, Jan 19 (Reuters) - Talks between Atlantia ATL.MI and a consortium of investors led by Italy's Cassa Depositi e Prestiti (CDP) are dragging on, three sources close to the matter said, adding a binding offer for the group's motorway unit would likely slip beyond January.

The negotiations are part of an effort by the infrastructure group and the Italian government to end a dispute that started in 2018 after a bridge run by the Atlantia's motorway unit Autostrade per l'Italia collapsed, killing 43 people.

Uncertainty over the future of Autostrade is expected to continue after January, the sources said, adding a lengthy due diligence on Autostrade and an ongoing political crisis in Italy were making things trickier than expected.

Italian state-backed lender CDP teamed up with Australian infrastructure fund Macquarie (MQG) and private equity group Blackstone BX.N in October to buy the 88% stake Atlantia owns in Autostrade.

Germany's Allianz ALVG.DE , France's EDF Invest, DIF Infrastructure and China's Silk Road fund own the remaining 12% of Autostrade.

Atlantia, which is controlled by the powerful Benetton family, has committed to relinquish control of Autostrade to mend fences with the government over Autostrade's motorway concession.

Atlantia is also working on an alternative plan that envisages the spin-off and listing of Autostrade.