The Biden administration on Wednesday accused three US companies of sending to China blueprints and technical drawings for satellite and rocket technology and other defence prototypes.

The Commerce Department levelled the allegations as it blocked the three companies from exporting items to foreign countries for 180 days.

That punishment, known as a temporary denial order, is regarded as among the most severe civil sanctions available to the department.

The companies – Quicksilver Manufacturing Inc., Rapid Cut LLC, and US Prototype Inc. – provide 3D printing services to customers that include manufacturers of space and defence technology.

The Commerce Department says the customers would send blueprints and drawings to the companies that they wanted printed – and that the companies in turn would send that work to China, presumably as a way to cut costs.

That transaction would have required US government approval, but no permission was requested, the Commerce Department said.

“Outsourcing 3D printing of space and defence prototypes to China harms US national security,” Matthew Axelrod, an assistant secretary of commerce for export enforcement, said in a statement.

“By sending their customers’ technical drawings and blueprints to China, these companies may have saved a few bucks – but they did so at the collective expense of protecting US military technology.”

The 11-page Commerce Department order does not allege that the blueprints wound up being exploited by the Chinese military, but it does say the actions present “serious national security concerns”.

US officials have warned in the past about blurred lines between the military and private industry.

The Commerce Department used customers of the companies to check their records to ensure that their intellectual property was not compromised.

The companies use the same rental postbox in Wilmington, North Carolina. Requests for comments sent through the websites of Quicksilver Manufacturing Inc. and Rapid Cut LLC were not immediately returned. https://www.scmp.com/news/world/united-states-canada/article/3180946/three-us-companies-sanctioned-sending-defence