Despite reaching an £452m restitution settlement with Marsh & McLennan Companies (MMC), the New York attorney general Eliot Spitzer warned his investigations are not over yet.

Hinting that more lawsuits could be on the way, Spitzer said: "I don't like to define the parameters of settlements that haven't been negotiated. But other companies should be examining these documents."

He said the US insurance industry was "rife with corruption" and "many more" criminal charges will be brought against executives guilty of bid-rigging.

MMC has neither confirmed nor denied allegations of kickbacks and bid-rigging. But the company has issued a statement in which it apologised for "unlawful" and "shameful" conduct.

As a result of the investigation, MMC plans to introduce sweeping reforms across its global business. In the UK a business plan is expected to be made public within weeks.

The £452m restitution is to be used to establish a fund to compensate clients who were misled by the company. The money will be paid back over a four-year period beginning in June. Aggrieved clients in California will be given £70m, while those in New York will get £50m of the fund. The fund means that MMC will escape paying fines to New York state.

Spitzer told the industry to watch closely to see how the case developed.