The Nuclear Regulatory Commission wrongly approved the sale and decommissioning of a Massachusetts nuclear power plant and should halt both immediately, the state’s attorney general told the commission in a Sept. 4 filing with the federal agency.

Commission staff violated NRC regulations and the National Environmental Policy Act by approving the license transfer and exemption requests for the Pilgrim Nuclear Power Station “even though it is clear today that insufficient funds exist” in the decommissioning trust fund to protect the public and the environment, Attorney General Maura Healey (D) said in the request to the NRC.

Entergy Corp. shut...