Volkswagen chief executive Matthias Mueller met with the head of the US Environmental Protection Agency in Washington on Wednesday as the company seeks to resolve its pollution cheating woes.

Mueller met with EPA administrator Gina McCarthy one day after the agency, along with California's Air Resources Board, rejected Volkswagen's recall plans for its diesel cars equipped with illegal emissions cheat devices.

Those plans, CARB said, "are incomplete, substantially deficient, and fall far short of meeting the legal requirements" to rectify the emissions problem, and the EPA said in a statement that it agreed with the conclusion.

The EPA said Wednesday after Mueller left that it "appreciated the conversation with Volkswagen," but gave no details on his discussion with McCarthy.

"We will continue to work toward a solution," the agency said in a statement.

The German automaker is under pressure to fix nearly 600,000 of its cars in the US equipped with illegal "defeat devices" that concealed emissions of poison gases that violate regulations in a number of countries.

The issue, which extends to 11 million VW, Audi and Porsche 2.0 and 3.0 liter diesel cars worldwide, has severely damaged Volkswagen's reputation and spawned a host of investigations. In the United States alone, the German company is facing potentially tens of billions of dollars in fines over the scandal.

Its first proposal to fix the 2.0 liter cars was rejected by CARB and EPA on Tuesday.

"Volkswagen made a decision to cheat on emissions tests and then tried to cover it up," said CARB chair Mary Nichols in a statement.

"They continued and compounded the lie, and when they were caught they tried to deny it. The result is thousands of tons of nitrogen oxide that have harmed the health of Californians."

In response, Volkswagen said it was working with outside advisers "to develop a swift, fair and independent program, which will provide a comprehensive remedy for our customers."

"We are committed to working cooperatively with CARB and other regulators."

The company continues to be accused of foot-dragging in addressing the problem.

On January 4, the US government sued Volkswagen for installing the defeat devices on its diesel cars in the Untied States between 2009 and 2015.