PHILADELPHIA - Cigna Corp. shares fell as much as 4.6 percent yesterday, a day after a federal judge blocked a $200 million settlement of doctors' lawsuits over unpaid medical claims, ruling the insurer used "underhanded maneuvers" to obtain the agreement.

Shares of Philadelphia-based Cigna, the third-biggest U.S. health insurer, fell $1.24 to close at $42.03 in trading on the New York Stock Exchange.

The shares, which have fallen 53 percent over the last 12 months, traded as low as $41.30 earlier yesterday.

Cigna is among a number of health insurers facing suits over medical claims payments before U.S. District Judge Federico Moreno in Miami.

The decision Thursday bars Cigna from proceeding with the settlement of an Illinois suit covering 400,000 doctors who saw patients in Cigna preferred-provider plans. A federal judge in Illinois already had given preliminary approval to the accord.

"The general language that Moreno used was pretty strong," said Eric Veiel, who follows managed-care stocks for Deutsche Bank. "It doesn't look like there's going to be any back-door way to get these issues resolved."

Cigna officials said they didn't believe that they'd mishandled the settlement and would wait to see which federal judge would be assigned to review it.

"We don't believe the injunction affects the terms of the settlement, which we believe are fair and reasonable to all parties," said Wendell Potter, a company spokesman.

Shares of some other health insurers facing similar lawsuits pending before Moreno, including UnitedHealth Group Inc. and WellPoint Health Networks Inc., also fell after the ruling.

Minnetonka, Minn.-based UnitedHealth's shares fell 2.2 percent, or $1.84, to $81.92. Shares of Thousand Oaks, Calif.-based WellPoint fell 56 cents to $70.69. UnitedHealth is the largest U.S. health insurer, followed by Aetna Inc.

Moreno, assigned by a federal judicial panel in 2000 to oversee class action suits against Cigna, Aetna, UnitedHealth and WellPoint over insurance-payment disputes, said Cigna officials tried to avoid having him review the settlement's fairness by filing it in federal court in Illinois.

The settlement would resolve doctors' claims against Cigna pending in Illinois and before Moreno.

The judge said in a 13-page decision that he couldn't "turn a blind eye to the underhanded maneuvers Cigna took to obtain this settlement agreement."

Under the agreement in the Illinois case, Cigna would have an outside reviewer examine billing claims that were denied since January 1996. The insurer also would create a $10 million fund to compensate doctors for claims that weren't processed quickly enough and pay interest on claims more than 30 days overdue.

Doctors started filing lawsuits in 1999 accusing insurers of intentionally denying claims or delaying payments as part of a plan to put profits ahead of patients.

Earlier this year, Moreno denied class action status for suits by patients who claimed the companies skimped on medical care. He allowed the doctors' claims to proceed as a class action.

In his decision, Moreno criticized the insurer's bid to transform the Illinois settlement into a nationwide resolution of all doctor's medical-payment claims to avoid his jurisdiction over the cases.

Instead of bringing the settlement before him, Cigna and some plaintiffs' lawyers in Illinois brought before the case to U.S. District Judge Patrick Murphy in East St. Louis, who wasn't familiar with the case's history, Moreno said.

"Cigna snookered both this court and Judge Murphy in Illinois in an obvious attempt to avoid this court's jurisdiction," Moreno wrote in the opinion.