The spotlight has fallen again on the role played by the world's largest interdealer brokers in the rigging of benchmark interest rates, following reports that Icap is being formally investigated by UK regulators over the possible participation of its brokers in the scandal.

The UK's Financial Services Authority officially notified Icap in March last year that it was investigating the broker as part its wider investigation of Libor fixing, and had assigned seven of its 50-strong team working on the probe to the broker, the Financial Times reported today.