The Internet Archive has been hit with 550 “false” demands to remove “terrorist propaganda” from its servers in less than a week.
The demands came via the Europol net monitoring unit and gave the site only one hour to comply.
The Internet Archive said the demands wrongly accused it of hosting terror-related material.
The website said the requests set a poor precedent ahead of new European rules governing removal of content.
If the Archive does not comply with the notices, it risks its site getting added to lists which ISPs are required to block.
The Internet Archive, which uses the archive.org web address, is a non-profit organisation that lets people save and visit pages that might otherwise have been lost from the net.
In a blog, the website’s Chris Butler said that it had received notices identifying hundreds of web addresses stored on archive.org as leading people to banned material.
However, Mr Butler said, the reports were wrong about the content they pointed to, or were too broad for the organisation to comply with.
Some of the requests referred to material that had “high scholarly and research value” and were not produced by terror groups, he said.
Others called for the delisting of massively popular links that led people to “millions” of items.