Bristol-Myers Squibb, the US pharmaceuticals group, is beefing up its banking team ahead of possible takeover approaches from rivals, notably Sanofi-Aventis, by retaining the services of three Wall Street banks.

People familiar with the companies told the Financial Times that the US group had in the past week appointed Lehman Brothers to work alongside Citigroup and Morgan Stanley to examine its options ahead of an expected takeover approach from Sanofi.

The move is seen as a step towards creating a bidding war for the $51bn (€39bn) BMS by attracting rival pharmaceuticals groups such as Pfizer, Schering-Plough and Merck.

One French banker said Sanofi had been “caught cold” by this week’s leaked report of its plans to bid for BMS. Sanofi has yet to hire any banks.

A settlement with federal prosecutors, imposed on BMS after an accounting scandal, will expire in June – coinciding with an expected court decision on whether its crucial US patent is valid for Plavix, a risk it shares with Sanofi. The two companies recently held informal talks on ways to work together.

Felix Rohatyn, the veteran financier and former US ambassador to France now working for Lehman Brothers, is thought to be acting as a transatlantic liaison between the two groups.

However, the bankers denied reports that the two had signed an initial merger agreement. BMS declined to comment on Tuesday.

Sanofi has the advantage of being able to extract more synergies than most other bidders by eliminating the cost for BMS of royalties paid to the French group for Plavix.

Morgan Stanley was appointed last year by BMS to advise on strategic options.