The United States has launched an investigation into Germany to determine whether there has been underpayment for innovative pharmaceutical products affecting trade in the US.

"This investigation will seek to determine whether persistent underpayment for innovative pharmaceutical products by Germany is unreasonable or discriminatory and burdens or restricts US commerce," said US Trade Representative Jamieson Greer.

"President Trump has made clear that American patients should not be shouldering a disproportionate share of global pharmaceutical research and development," said Greer.

"I am particularly concerned with news that Germany is fast-tracking legislation that would further reduce its spending on innovative pharmaceuticals," Greer said.

He said this was a "serious step backwards at a time when our trading partners need to step up and start paying their fair share to fund innovative pharmaceutical research and development."