The troubled news division of CBS was haunted on Wednesday by a controversy from the past when Dan Rather, its former anchor, filed a $70m lawsuit against the company and three former superiors, accusing them of violating his contract and tarnishing his reputation.

The suit stems from a report Mr Rather presented three years ago questioning President George W. Bush’s service in the Texas Air National Guard. Mr Rather was forced to relinquish his post as anchor of the television network’s evening news after the authenticity of Vietnam-era documents used to support the report could not be verified.