The U.S. Environmental Protection Agency on Friday ordered states to stop blocking contaminated waste from a fiery train derailment in Ohio from being sent to hazardous waste storage sites around the nation.

A handful of politicians and states have sought to block shipments from East Palestine, including Oklahoma Gov. Kevin Stitt, who last week said he had stopped waste from the derailment from coming into his state.

EPA Administrator Michael Regan said there was no reason for states to block shipments of the type of waste that certified facilities routinely handle every day.

OHIO AG SAYS NORFOLK SOUTHERN ‘RESPONSIBLE’ FOR ECONOMIC AFTERMATH OF TOXIC TRAIN CRASH

"This is impermissible and this is unacceptable," he said.

In a letter sent to all states, the EPA said that blocking the shipments would likely violate a federal law dealing with the interstate transport of waste as well as the Commerce Clause of the U.S. Constitution, which the agency said limits the power of states to stop the movement of hazardous waste.

Although it's not clear what steps the EPA might take if states don't cooperate, the agency told railroad Norfolk Southern on Friday that it expects the company to take legal action if it is unable to ship the waste to certified disposal facilities.

A large plume of smoke rises over East Palestine, Ohio

The Environmental Protection Agency has ordered states to stop rejecting waste shipments from East Palestine, Ohio. ((AP Photo/Gene J. Puskar))

The EPA already ordered Norfolk Southern to cover the costs of cleaning up from the Feb. 3 derailment that toppled 38 rail cars. No one was hurt, but concerns over a potential explosion led state and local officials to approve releasing and burning toxic vinyl chloride from five tanker cars and forced the evacuations of half the village.

Ohio this week filed a lawsuit against Norfolk Southern to make sure it pays for the cleanup and environmental and economic damage along with groundwater and soil monitoring in the years ahead.

Norfolk Southern has said it is committed to cleaning up the site and helping the community recover.

OHIO ATTORNEY GENERAL ANNOUNCES LAWSUIT AGAINST NORFOLK SOUTHERN OVER EAST PALESTINE DERAILMENT

Many residents remain worried about what they might have been exposed to and how it will affect the area in the years ahead. Government officials say tests over the past month haven’t found dangerous levels of chemicals in the air or water in the area.

The cleanup should be completed in about three months, Regan said on Friday.

So far, crews have removed nearly 5,500 tons of contaminated soil and 7 million gallons of wastewater from the area, according to the EPA.

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Three weeks ago, the agency briefly stopped contaminated waste from being removed from the area when concerns were raised about oversight of where it was being shipped to sites in Michigan and Texas. Hazardous waste sites in Ohio and Indiana also have received shipments in recent weeks.