After partially privatising ENAV last year via a stock market listing, the treasury owns 53 percent of the air controller. The stake is worth 1.07 billion euros (£953.1 million) at current market prices.

"There are very advanced negotiations on the project ... it will likely happen by the end of this year," one of the sources said.

Italy is running behind on its 2017 goal of 3.4 billion euros in privatisation proceeds. CDP is 80 percent owned by Italy's state but keeps separate financial accounts.

(Reporting by Stefano Bernabei, Antonella Cinelli in Rome and Francesca Landini in Milan, editing by Valentina Za)