June 3 (Reuters) - The U.S. Transportation Department said Monday it has imposed $2.5 million in civil penalties in total against Lufthansa, Air France unit KLM Royal Dutch Airways and South African Airways.

The civil penalties, the department said, are for significant delays in providing more than $900 million in refunds owed to passengers due to flights disrupted by the COVID-19 pandemic. Of the $1.1 million penalties imposed on KLM and Lufthansa, each carrier was credited $550,000 for refunds for non-refundable tickets on U.S. flights. (Reporting by David Shepardson)