ICAP, the world’s largest interdealer broker, is a major focus of the Libor rate-rigging probe and is being investigated by the UK financial watchdog for possible breaches of conduct rules.

The Financial Services Authority has assigned seven of the roughly 50 people working on its Libor probe to focus specifically on investigating ICAP, an internal FSA memo seen by the Financial Times says.

Michael Spencer, the former Conservative party treasurer who founded the company, has previously publicly downplayed the group’s role in the Libor scandal. Shortly after Barclays settled in June with the regulator over Libor rigging he said that the global regulatory investigations were not a “high concern” as his company was not “front and forward” in investigations and not directly involved in setting the rate.