In a highly unusual move by a state agency, Maryland insurance officials ordered a Washington-Baltimore health maintenance organization yesterday to postpone a 200 percent rate increase for an estimated 1,300 senior citizens.

The M.D.-Individual Practice Association (M.D.-IPA), which operates a special program under the direction of the U.S. Health Care Financing Administration for persons age 65 and over, has been charging each senior in the program $22.22 a month for medical coverage. The new rate, approved by the federal agency, would have practically tripled the rate to $62.13 a month per person if it were to take effect tomorrow as scheduled.

The agency's decision to block a federally approved rate increase for medical coverage is rare. Officials want the increase delayed for up to 60 days so that it can be reviewed.

Benefits also would have shrunk under the M.D.-IPA plan, officials said. M.D.-IPA, for example, would no longer reimburse patients for purchases of medications under the new rate plan.

M.D.-IPA officials contend the higher rates and reduced benefits are necessary to cover the organization's higher costs and limited federal reimbursement for Medicare expenses.

"But we do not necessarily subscribe to the same thought path," Deputy Insurance Commissioner Martha Roach said yesterday. She said her office plans to hold a public hearing, probably in late January, to examine the basis for the rate increase and to decide whether it is justified.

Officials from M.D.-IPA as well as senior members who would be affected by the rate increase would be permitted to testify at the hearing, Roach said. The state's actuary then would review the rate filing to see that it is justified, she said.

Roach said that M.D.-IPA must have state approval to implement its rate increase, despite assertions by M.D.-IPA that federal approval overrides state actions.

"We . . . . think we have the authority to regulate . . . . because {the medical care} is a product offered in Maryland to Maryland consumers," Roach said.

M.D.-IPA spokeswoman Andrea Stillman said that her organization is working with federal, state and local officials to "work out an amenable and appropriate agreement" and is willing to postpone the rate increase if federal officials approved.

Health Care Financing Administration official Kevin Moley said his agency had no objection to the delay.

Roach said this is the first time that her department has challenged a federally authorized rate change for medical coverage. Moley said he did not know of any comparable actions by agencies in other states.

"It would appear to be a regulatory precedent for the state to come in and block something that the federal government has approved," Moley said.

However, Moley also said that insurers contracting with the federal health care agency must be in compliance with the laws of the state in which they operate. That would include state laws requiring state approval of rates, he said.

Moley said that the federal agency, in approving higher rates for M.D.-IPA, had determined that the changes were in compliance with federal statutory requirements. He said that he hopes "the state wouldn't do anything that wouldn't be in the interest of Medicare beneficiaries."