Sen. Edward J. Markey (D-Mass.) said Monday that permits for exporting natural gas may violate the Energy and Policy Conservation Act of 1975, which banned overseas sale of oil or gas.

An executive order by President Gerald R. Ford in 1976 delegated rule-making and exemption permits to the Commerce Department. Markey, a foe of liquefied natural gas exports, said Commerce has not issued such guidelines.

The Massachusetts Democrat said that the Energy Department’s seven LNG export permits and licenses for gas exports to Canada and Mexico through pipelines could be open to a lawsuit under the Administrative Procedure Act.