FILE PHOTO: A locomotive engine of German railway Deutsche Bahn is seen at the main train station in Frankfurt, Germany, March 27, 2019. REUTERS/Kai Pfaffenbach

BERLIN (Reuters) - Deutsche Bahn is in exclusive talks with U.S. buyout group Carlyle CG.O over the sale of the German rail operator's Arriva international passenger transport unit, a person familiar with the matter said on Friday.

The German rail operator is also still preparing for a potential flotation of Arriva, the person said.

Arriva, which employs 53,000 people across Europe and is expected to be valued at 3-4 billion euros ($3.35-$4.5 billion), runs British rail franchises including Northern and the London Overground as well as buses around the country.

Previously, Apollo APO.N had been working on a competing offer.

Deutsche Bahn and Carlyle weren’t immediately available to comment.