FRANKFURT, Sept 20 (Reuters) - Volkswagen has ordered an external investigation after U.S. regulators found software the carmaker designed for diesel cars gave false emissions data, its CEO said on Sunday, adding he was "deeply sorry" for the violation of U.S. rules.
"I personally am deeply sorry that we have broken the trust of our customers and the public," Martin Winterkorn said in a statement published by the carmaker on Sunday.
The U.S. Environmental Protection Agency (EPA) on Friday said the software deceived regulators measuring toxic emissions, adding Volkswagen could face fines of up to $18 billion as a result of the violation.
"We do not and will not tolerate violations of any kind of our internal rules or of the law," Winterkorn added.
(Reporting by Christoph Steitz; Editing by Mark Potter)