COLUMBUS -- One prominent insurer sued Monday by Ohio Attorney General Mark Dann over bid-rigging allegations says it's already paid up plenty to Ohioans over similar claims.

Dann announced late Monday he was suing a slew of insurers, including some of the industry's biggest names, over allegations they colluded to raise the price of commercial insurance premiums using false bids.

Dann filed suit Aug. 24 in the Cuyahoga County Common Pleas Court against Ohio's biggest commercial-insurance broker and the subsidiaries of four major insurance companies.

All five named in the action have already settled bid-rigging suits in New York, Connecticut, Pennsylvania and Illinois. New York and federal regulators collected $1.64 billion in settlement last year from a range of insurance-market participants, Bloomberg reported.

As in suits in New York, Connecticut and Illinois, giant insurance broker Marsh & McLennan heads Dann's list of suspects in the suit. Marsh & McLennan Cos. (MMC) settled a similar suit in 2005 with former New York Attorney General Eliot Spitzer for $850 million.

Dann also is suing insurers including AIG, the Hartford, Chubb and ACE for colluding with MMC in the scheme. "Our investigation has produced evidence of blatant violations of the antitrust laws that have cost Ohio businesses millions of dollars," he stated.

But Ohio businesses have already "overwhelmingly" accepted a $35 million settlement that Marsh & McLennan earmarked for the state from its $850 million payment to Spitzer, said MMC spokesman Mike Kachel. "We intend to defend this claim vigorously," he told Bloomberg.

Chubb Corp. pledged to "vigorously" contest Dann's allegations, spokesman Mark Greenberg told Reuters. He said the company had cooperated fully with state investigators in Ohio and other states.

Hartford Financial Services "categorically denies" Dann's allegations and will also "vigorously" defend itself, the company said in a statement. The insurer said it was "disappointed that Dann did not discuss the action before filing suit.

Bermuda-based Ace Ltd. recently settled a lawsuit with Pennsylvania Attorney General Tom Corbett for $9 million after earlier agreeing to repay customers $40 million in a similar suit to Dann's.