PARIS--Vivendi SA's French telephone company SFR and local competitor Bouygues Telecom entered exclusive talks Monday to share parts of their mobile-phone networks in France, the latest cost-saving move by French operators as they reel from a brutal price war.

SFR and Bouygues--respectively, France's No. 2 and No. 3 mobile operators by number of subscribers--said late Monday that they hope to come to a strategic agreement by the end of the year to share parts of their mobile phone networks, using a model similar to those already in operation in other countries.

The two companies said their proposed network-sharing agreement would allow them to boost their geographic coverage and face "the challenge of investing in super high bandwidth networks."

But they added that they would retain an "independent capacity for innovation, and total commercial independence."

Network-sharing deals let operators share towers, and in some arrangements even antennas, transmitter equipment and maintenance personnel. That can allow significant savings as operators roll out expensive network equipment.

Since last fall, France's four main phone operators, including incumbent Orange SA, and low-cost upstart Iliad SA, have been privately discussing such an agreement, according to people familiar with the matter, as a way to cope with a price war started when Iliad launched its Free Mobile operator in January 2012.

Network sharing is popular in Europe's fragmented telecommunications landscape, where more than 40 companies own operators across the union's 28 countries.

European antitrust regulators have been reluctant to allow mergers within individual countries, and mobile operators often regard network sharing as the next-best thing.

France has lagged behind its neighbors in network sharing, however, because government and regulatory policies have looked to lower prices for consumers by increasing competition among network owners.

But now, under a new Socialist government, ministers have been receptive to arguments from companies like Orange that low prices are spoiling the telecom market and hurting France's industrial base.

Last fall, the French government asked the independent antitrust watchdog to review network-sharing deals. In March, the watchdog said it was ready to bless them in certain instances--such as in rural areas, or for physical towers in cities.

After Monday's announcement of the SFR-Bouygues talks, French Industry Minister Arnaud Montebourg and Technology Minister Fleur Pellerin said in a joint statement that network-sharing agreements are part of the government's strategy, and "appear particularly appropriate when margins are more constrained, as is the case currently."

Write to Sam Schechner at sam.schechner@wsj.com

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