Mercedes-Benz will pay a $13 million penalty to US safety regulators for a string of reporting failures involving recalled vehicles.

The German automaker agreed to the payment in a settlement with the National Highway Traffic Safety Administration.

Last year, the agency opened an investigation into recall reporting lapses by Mercedes involving more than 1.4 million vehicles.

The investigation covered allegations of recall notification letters being sent too slowly to vehicle owners as well as slow reporting of safety problems to the agency.

The settlement also addresses flaws with the operation and functionality of Mercedes' internet site that lets vehicle owners check for recalls by their vehicle identification numbers, the agency said Wednesday in a statement.