US authorities have hit Lufthansa with a record $4 million penalty after finding the airline discriminated against over 100 Jewish travelers by blocking them from boarding a flight in 2022, officials said Tuesday.

The 128 passengers were denied boarding to a connecting flight after a few did not follow instructions, including anti-Covid mask requirements, on a flight from the United States to Germany, US transport authorities said.

The airline did not immediately reply to an AFP request for comment.

The US Department of Transportation said the penalty over the boarding refusal on May 3, 2022 in Frankfurt was the largest it had issued for a civil rights violation.

The travelers — who wore distinctive garments like black hats and jackets — told investigators they were treated as if they were one group even though many weren’t flying together and didn’t know each other.

Lufthansa denied boarding “to everyone for the apparent misbehavior of a few, because they were openly and visibly Jewish,” DOT authorities said in a filing.

The problem began when the captain of the first flight reported to Lufthansa security that some passengers were not following rules, including wearing of face masks during the trip and not standing in groups in aisles or near emergency exits.

DOT authorities received over 40 discrimination complaints from Jewish passengers in this case.

Lufthansa told DOT that it has publicly apologized on numerous occasions for barring the passengers from continuing their trips, but denied any suggestion that any of its employees engaged in any form of discrimination.