The news is a blow to the incumbent, Carat. It comes at an already tough time for the Aegis-owned network, which is experiencing problems in its French home market, following the departure of several top executives and the review of other key accounts.
Carat won the consolidated Renault account in 2000, as part of a cost-cutting initiative by the car manufacturer. The network began working on the business in January 2001. Previously, it was held by agencies on a market-by-market basis, with Optimedia handling it in ten of Renault's 16 markets.
France is Renault's biggest market, where it spends an estimated £160 million. Its UK spend is £57 million.
OMD Europe could be in the running to pitch for the account, as it handles the pan-European Nissan business and Renault operates an alliance with the Japanese car-maker.
However, it is unclear if Renault and Nissan are considering consolidating the business with the Nissan account.
Renault is currently on a high after it reported better-than-expected profits for the first six months of the year. Its income grew by 29 per cent to £990 million and it forecast that demand for its cars could rise by 2 per cent in Western Europe this year.
Carat's president in France, Henri Le Menestrel, recently left the agency.
His departure follows that of Carat's finance director and head of research, Rene Saal. Clients including LVMH, Universal Music and La Poste are also said to be reviewing in France.
Speculation has linked the departed directors with KR Media, the start-up agency founded by the former Aegis Media Europe chiefs Eryck Rebbouh and Bruno Kemoun. However, KR Media denied that Le Menestrel would be joining its ranks.
Jerry Buhlmann, the chief executive of Aegis Media Europe, denied that Renault was reviewing. He said: "It's definitely not true; this is part of a web of rumours. Renault is a very substantial European account and we're close to it every day."
Meanwhile, recent reports suggested that Carat has won the one billion euro pan-European Unilever buying account. However, Unilever said it has not yet taken a decision and will announce the result on 18 October.
No-one at Renault was available to comment on the story as Campaign went to press.