The two automakers said earlier this week they planned to join forces in a 50-50 share merger to create the world's fourth-largest automaker, seeking scale to cope with costly new technologies and slowing global demand.

They said they aimed to reach a binding deal on the $50 billion merger "in the coming weeks".

The source said the two groups were at work to finalise all the merger details and they hoped to sign a binding memorandum of understanding in "three-four weeks".

"This means the final agreement should be signed by early December, or by Christmas at the latest," the source said, confirming a report published earlier on Saturday in La Stampa daily newspaper.

(Reporting by Giulio Piovaccari; Editing by Christina Fincher)

Stocks treated in this article : Peugeot, Fiat Chrysler Automobiles, Exor N.V.