French restaurant chain Buffalo Grill has said its fourth-quarter sales fell 0.9% to €68m (US$73.4m), hit by allegations that the company illegally imported banned British beef.

Buffalo Grill, which is currently under investigation for serving British beef in its restaurants during the ban, said sales in January were off by around 29% from expected levels.

The company said that its 2002 sales rose 4.9% to €284.6m.

Buffalo Grill’s two top managers remain in prison as the investigation continues, reported Reuters.