Federal regulators are urging states to stockpile potassium iodide near nuclear power plants to help protect nearby residents in a radiation emergency.

The Nuclear Regulatory Commission, acting on a nearly two-decade-old recommendation, said Wednesday it now considers stockpiling potassium iodide pills near reactor sites "reasonable and prudent" to protect people against thyroid cancer during a nuclear accident.Any decision on whether to stockpile the drug would be up to states and local authorities, but the NRC said the federal government would pay for the purchase and in some cases make the drug availthat also includes evacuation and sheltering.

Potassium iodide, if taken shortly after exposure to radiation, blocks the thyroid gland's intake of radioactive iodine, providing protection against thyroid cancer and other diseases.

But for years the NRC has refused to call for such stockpiling, although a presidential commission that investigated the 1978 Three Mile Island nuclear accident strongly urged that the pills be available for rapid distribution near reactor sites in event of an emergency.

On Wednesday, the NRC said that because of additional evidence on the use of such pills in connection with the 1986 Chernobyl nuclear accident, it now believes keeping them for rapid distribution near nuclear reactors was prudent in many cases.

"Some states may find the use of potassium iodide appropriate as a supplemental protective action under certain local conditions," the NRC said, reversing a policy that has been in effect since 1985 that called for pills to be made available only for emergency workers.