Maryland Attorney General Brian Frosh said in a statement that his state and others plan to sue Volkswagen AG over the environmental damage done by the carmaker's so-called defeat devices designed to cheat pollution-control tests.
Frosh said Maryland is acting in coordination with the attorneys general of New York and Massachusetts, among others.
He said a press conference is scheduled for Tuesday to release more details about the suit.
New York state said last month it had reached a "partial settlement" with the automaker -- joined by 43 other states -- worth a total of $603 million.