By David Shepardson

Twitter Inc, Reddit and a group representing major internet firms backed two documentary film groups that have challenged the Trump Administration's 2019 rules requiring nearly all U.S. visitors to disclose social media user information from the prior five years.

In court papers filed on Thursday, the social media sites and the Internet Association, representing Facebook, Amazon.com, Alphabet and others, said the rules force foreign nationals "to surrender their anonymity in order to travel to the United States" and "chill a vast quantity of speech and associational activity."

The Doc Society and the International Documentary Association filed suit in U.S. District Court in Washington, D.C., in December. They said they regularly collaborate with non-U.S. filmmakers and warn that visitors must "consider the risk that a U.S. official will misinterpret their speech on social media, impute others' speech to them, or subject them to additional scrutiny or delayed processing because of the views they or their contacts have expressed."

The latest filing comes amid an escalating feud between President Donald Trump and tech companies. Twitter on Friday hid a Trump tweet behind a warning for the first time. It came hours after Trump signed an executive order threatening Silicon Valley social media firms with new free speech regulations, after Twitter added a fact-checking tag to two previous tweets.

The State Department rules require disclosure of all social media handles used over the prior five years by U.S. visa applicants, including ones under pseudonyms, on 20 platforms.

Applicants must disclose accounts on Facebook, Instagram, Flickr, Google+, YouTube, LinkedIn, Myspace, Pinterest, Reddit, Tumblr, Twitter, Vine and Chinese sites Douban, QQ, Sina Weibo, Tencent Weibo, and Youku; Russian social network VK; Belgian site Twoo; and Latvian site Ask.fm.

The Justice Department has argued in court papers that "information gleaned from social media profiles can be used to determine activity, ties, or intent that would be grounds for visa denial, including criminal acts."

The State Department says the rules were prompted by Trump's 2017 order requiring heightened vetting of visa applications. It previously collected contact information, travel history, family information, and prior addresses.

The department receives more than 14 million applicants annually. The only travelers exempted from the social media rules are diplomatic and official travelers.

(Reporting by David Shepardson; Editing by Dan Grebler)