The Securities and Exchange Commission may take enforcement action against Volkswagen over the German automaker's involvement in the "dieselgate" emissions scandal, according to VW's annual report.

The automaker said the agency is "piling on" and that the agency's complaint is without merit.

The agency told Volkswagen that in January 2017 it opened a formal investigation, which is ongoing and may result in an enforcement action, according to the annual report. The SEC can issue fines and other civil penalties for violations of securities law.

The SEC has asked Volkswagen for information on potential securities law violations over certain investments the company may have sold to investors. The agency is looking for evidence determining whether the automaker failed to disclose information about vehicles that didn't comply with U.S. emission standards when it issued certain securities to investors.

The SEC declined to comment to CNBC. Volkswagen said the complaint is "legally and factually flawed" and that the automaker will "contest it vigorously."

One of the world's largest carmakers, Volkswagen was rocked by reports first surfacing in 2015 that it had been caught cheating on emissions tests in the United States. The subsequent scandal cost Volkswagen billions of dollars to settle and forced the automakers to recall millions of vehicles.

Here is Volkswagen's full statement to CNBC: