Wikipedia administrators have imposed a ban on page edits from computers at the US House of Representatives, following "persistent disruptive editing".
The 10-day block comes after anonymous changes were made to entries on politicians and businesses, as well as events like the Kennedy assassination.
The biography of former US defence secretary Donald Rumsfeld was edited to say that he was an "alien lizard".
One staffer said they were being banned for the "actions of two or three".
Edits from computers using the IP address belonging to the House of Representatives have been banned before, following similar acts of vandalism.
The latest block comes after rogue edits were brought to light by a Twitter feed, @congressedits, which posts every change made from the government-owned address.
One of the acts highlighted was an alteration to the page on the assassination of John F Kennedy, which was changed to say that Lee Harvey Oswald was acting "on behalf of the regime of Fidel Castro".
An entry on the moon landing conspiracy theories was changed to say they were "promoted by the Cuban government".
Another entry, on the Ukrainian politician Nataliya Vitrenko, was edited to claim that she was a "Russian puppet".
The biography of former US defence secretary Donald Rumsfeld was revised, describing him as an "alien lizard who eats Mexican babies".
However the edit that finally brought administrators to ban anonymous edits from the House IP address was made on the entry for media news site Mediaite, describing the blog as "sexist transphobic" and saying that it "automatically assumes that someone is male without any evidence".
Mediaite had previously run a story on the rogue edits from congressional computers.
Jimmy Wales, the founder of Wikipedia, told the BBC that the incident did not surprise him, and vandalism has "always gone on and it always will".
But he said that the @congressedits Twitter feed may have been counter-productive.
"There is a belief from some of the [Wikipedia] community that it only provoked someone - some prankster there in the office - to have an audience now for the pranks, and actually encouraged them rather than discouraged them."
He added: "Maybe someone at the House of Representatives better think about their IT staff - they might be hunting them down this very moment."
UK government edits
Earlier this year, the BBC discovered that the phrase "all Muslims are terrorists" was added to a page about veils by users of UK government computers.
That followed a report by the Liverpool Echo which found that insults had been added to the entry for the Hillsborough disaster.
Wikipedia allows any user to make changes to a page, even anonymously.
However, the changes are policed by volunteers, known as Wikipedians, who can reverse false edits, and even impose bans on users who continually flout the site's editing rules.
Wikipedians have been warning editors from the House of Representatives since March 2012, and moved to block the address for one day earlier this month.
On Thursday, the IP address was blocked for 10 days, but one staffer protested that they were being punished for the actions of a few.
"Out of over 9,000 staffers in the House, should we really be banning this whole IP range based on the actions of two or three?
"Some of us here are just making grammatical edits, adding information about birds in Omsk, or showing how one can patch KDE2 under FreeBSD."
Another user from the Hill was quick to dismiss suggestions that the rogue edits were made by elected officials.
"I think the probability is near zero that these disruptive edits are being done by a member of Congress."