Fish distributor Deutsche See is suing Volkswagen for misrepresenting a fleet of vehicles it leased as environmentally friendly, becoming the first major German fleet customer to sue VW over its diesel-test cheating, according to Reuters.

This is the first case brought by a corporate fleet customer in its home market.

Bremerhaven-based Deutsche See, which leases about 500 vehicles from Volkswagen, said it had been unable to reach an out-of-court settlement. Talks had broken down after Volkswagen replaced the relevant managers with lawyers and PR managers, according to the Rueters report.

German tabloid Bild am Sonntag said Deutsche See was suing for 11.9 million euros ($12.8 million).

"Deutsche See only went into partnership with VW because VW promised the most environmentally friendly, sustainable mobility concept," said a statement from Deutsche See, which won a sustainability prize in 2010, as reported by Reuters.

Volkswagen admitted in September 2015 it had used software to manipulate diesel-emissions tests in the United States.