By Pamela Barbaglia and Gwénaëlle Barzic
LONDON/PARIS (Reuters) - Rival consortia led by U.S. buyout fund KKR
The two other bidding groups are led by Australian investment firm Macquarie and U.S. infrastructure fund I Squared Capital respectively, four sources close to the deal told Reuters.
Altice, which runs France's second biggest telecom operator, is selling a stake of between 40 and 60 percent of its fibre network unit in a deal that could be worth up to 3.6 billion euros (3.14 billion pounds), the sources said.
Binding offers are due towards the end of November and the deal is expected to be wrapped up by late December.
The sale has also drawn interest from a series of long-term investors.
Canadian pension fund manager OMERS has teamed up with Allianz while Singapore's sovereign wealth fund GIC has joined forces with I Squared Capital, one of the sources said.
Altice and Allianz declined to comment. KKR, Macquarie, I Squared Capital, GIC and OMERS were not immediately available for comment.
($1 = 0.8762 euros)
(additional reporting by Arno Schuetze in Frankfurt and Mathieu Rosemain in Paris, editing by Silvia Aloisi)