About 200,000 N95 masks were diverted to the US as they were being transferred between planes in Thailand.

According to the Berlin authorities who said they had ordered the masks for the police force.

Andreas Geisel, the interior minister for Berlin state, described the diversion as “an act of modern piracy” and appealed to the German government to demand Washington conform to international trading rules.

“This is no way to treat trans-Atlantic partners,” Geisel said.

“Even in times of global crisis there should be no wild west methods.”

The German reports said the masks had been made by a Chinese producer for the US company 3M, but the firm issued a statement on Friday night saying, “3M has no evidence to suggest 3M products have been seized.

3M has no record of any order of respirators from China for the Berlin police. We cannot speculate where this report originated.”

The German allegations added to a chorus of complaints about the Trump administration’s practice as the US wields its clout in a marketplace for scarce medical supplies that is becoming a free-for-all, with nation competing against nation.

Valérie Pécresse, the influential president of the Île-de-France region, which includes Paris, described the race to get masks as a “treasure hunt”.

“I found a stock of masks that was available and Americans – I’m not talking about the American government – but Americans, outbid us,” Pécresse said.

“They offered three times the price and they proposed to pay upfront. I can’t do that. I’m spending taxpayers’ money and I can only pay on delivery having checked the quality,” she told BFMTV. “So we were caught out.”