FILE PHOTO: The U.S. Environmental Protection Agency (EPA) sign is seen on the podium at EPA headquarters in Washington, U.S., July 11, 2018. REUTERS/Ting Shen

WASHINGTON (Reuters) - The top lawyers at the Environmental Protection Agency and Transportation Department told the California Air Resources Board Friday that the state’s actions in connection with a voluntary emissions deal with four automakers “appear to be unlawful and invalid.”

Ford Motor Co, Honda Motor Co, BMW AG and Volkswagen AG VOWG_p.DE in July agreed to adopt revised California vehicle emissions standards in exchange for some flexibilities offered by the state. The four automakers also agreed not to challenge the state's legal authority.

The letter -- copies of which were sent to the automakers chief executives -- said the automakers’ commitments “may result in legal consequences given the limits placed in federal law on California’s authority.” California did not immediately comment.