The US government has demanded designs for a 3D-printed gun be taken offline.
The order to remove the blueprints for the plastic gun comes after they were downloaded more than 100,000 times.
The US State Department wrote to the gun's designer, Defense Distributed, suggesting publishing them online may breach arms-control regulations.
Although the files have been removed from the company's Defcad site, it is not clear whether this will stop people accessing the blueprints. They were being hosted by the Mega online service and may still reside on its servers. Also, many links to copies of the blueprints have been uploaded to file-sharing site the Pirate Bay, making them widely available. The Pirate Bay has also publicised its links to the files via social news site Reddit suggesting many more people will get hold of the blueprints.
Cody Wilson, who founded Defense Distributed, told the BBC that the genie was out of the bottle. "Once people heard what happened, Pirate Bay has exploded. I'm sat here watching it now, seeing the downloads go up and up."
The Office of Defense Trade Controls Compliance emailed Mr Wilson a document demanding the designs be "removed from public access" until he could prove he had not broken laws governing shipping weapons overseas by putting the files online and letting people outside the US download them. Explosive force Mr Wilson said that Defense Distributed had complied with the International Traffic in Arms Regulations (ITAR) rules.
He said the rules were pretty convoluted, but he believed his project was exempt as Defense Distributed had been set up specifically to meet requirements that exempted it from ITAR. "Our gun operations were registered with ITAR." He said the letter was unclear in that the Office was conducting a "review" yet at the same time he had to remove the files. "They are stalling, they are going to make this review last as long as they can," he said. "They are getting a lot of political pressure." He added that he had taken legal advice about what to do next.
"We've also had offers of help from lawyers from all around the country," he said. He welcomed the US government's intervention, saying it would highlight the issue of whether it was possible to stop the spread of 3D-printed weapons. Unlike conventional weapons, the printed gun - called the Liberator by its creators - is made out of plastic on a printer. Many engineering firms and manufacturers use these machines to test prototypes before starting large-scale production. While desktop 3D printers are becoming more popular, Defense Distributed used an industrial 3D printer that cost more than £5,000 to produce its gun. This was able to use high-density plastic that could withstand and channel the explosive force involved in firing a bullet.
Before making the Liberator, Mr Wilson got a licence to manufacture and sell the weapon from the US Bureau of Alcohol, Tobacco, Firearms and Explosives. The Bureau told the BBC that any American could make a gun for their own use, even on a 3D printer, but selling it required a licence. Mr Wilson, who describes himself as a crypto-anarchist, said the project to create a printed gun and make it widely available was all "about liberty".