The BBC has discovered that the phrase "all Muslims are terrorists" was added to a page about veils.
Another edit deleted text in Cherie Blair's entry about the flat-buying scandal that made headlines in 2002.
The Liverpool Echo last week revealed that insults had been added to the entry for the Hillsborough Disaster.
Stevie Benton, from Wikimedia UK, told the BBC: "We find this kind of vandalism appalling."
Wikimedia UK is the local arm of the global Wikipedia Foundation, the charity set up by the online encyclopaedia's founder Jimmy Wales to support the thousands of volunteers who edit and maintain Wikipedia.
"Wikipedia is the encyclopaedia that anyone can edit," Mr Benton added.Continue reading the main story “Start Quote
It is shocking and cause for great concern”End Quote Nasima Begum Muslim Council of Britain
"This openness has led to an enormous reference work of great value. While vandalism does occasionally happen we are grateful to the many thousands of volunteers who write, edit and organise the content."
In an email, the Cabinet Office reiterated its statement on the matter.
"The amendments made to Wikipedia are sickening. The behaviour is in complete contravention of the Civil Service Code. It is entirely unacceptable."
It added: "The Civil Service Code applies at all times, and we take breaches very seriously. We have already announced an investigation to examine offensive edits to Wikipedia, and will look at other concerns raised."'Spells evil'
The BBC found more than a hundred instances of inappropriate editing, vandalism and deletion made by computers accessing Wikipedia through the two IP addresses known to be used by government machines.
A change made to the entry for "veil" in October 2006 added: "It should be noted that the word Veil, when the letters rearraged [sic], spells evil.Large parts of an entry about Cherie Blair were deleted
"Since the Veil is mostly worn by Muslims, and all Muslims are terrorists (with the argument for this being that all terrorists have been Muslim), this fact should be dually [sic] noted by all."
The comment was removed by a Wikipedia volunteer six minutes later.
Nasima Begum, a spokeswoman for the Muslim Council of Britain, told the BBC: "It is these types of attitudes that create an unnecessary climate of fear and hostility.
"It is shocking and cause for great concern that inflammatory comments like these should be sent from someone within the government."Removed paragraphs
As well as vandalism, large passages of text were deleted.
In 2002, Cherie Blair made a public apology after it had emerged she had bought two flats, at a discounted price, with help from convicted fraudster Peter Foster.
Paragraphs about the incident in Mrs Blair's Wikipedia entry were removed by a government PC in October 2005.
Later, a different user would revert the changes, arguing that they were "relevant to the subject's reputation".
The BBC was unable to reach Mrs Blair to discuss the matter. There is no indication that she had any knowledge of the changes.
Other edits made by government machines included:Continue reading the main story How edits were uncovered Wikipedia allows any web user to make changes to its pages, but this leaves a trace through the user's internet protocol (IP) address Changes are monitored by Wikipedia, but internet trolls have been known to post insulting material, which is usually swiftly removed Liverpool Echo reporter Oliver Duggan discovered that insults posted on the website's Hillsborough Disaster page had been made using computers within the government's internal intranet He confirmed this after referring to a list of 34 IP addresses used by the government released by former minister Angela Eagle in 2008 The BBC analysed two of the addresses - 126.96.36.199 and 188.8.131.52 - to find the edits contained in this article In the entry for the London bombings, links to websites detailing popular conspiracy theories were added. The article for former prime minister Tony Blair was deleted in its entirety and replaced with the words "he should be assassinated". Homophobic insults were added to the entry for newspaper columnist Richard Littlejohn. Celebrity chef Jamie Oliver, who has worked for the government on healthy eating initiatives, also had homophobic insults added to his page.
Mr Benton, from Wikimedia UK, praised the work of Wikipedia editors in correcting the changes.
"Edits of this nature are removed very quickly by the volunteers who write and edit Wikipedia," he said. "Often in a matter of minutes."
Edits made by government computers have come under close scrutiny following the Liverpool Echo's report showing how insulting remarks about Liverpool fans were added to the page detailing the Hillsborough Disaster.
The changes were identified by analysing edits made by two IP addresses - 184.108.40.206 and 220.127.116.11 - known to be connected to the Government Secure Intranet (GSI).
The GSI is used to allow government machines to connect to the internet securely.Investigation
The Cabinet Office has admitted that, due to the nature of its computer network, it would be almost impossible to track down who is responsible for the offensive remarks.
A spokesman said: "We are exhausting every option. Anyone with information should contact the Cabinet Office."
Unlike most people's home internet connections, where an IP address can sometimes be used to pinpoint one particular computer, large organisations tend to mask individual machines for security reasons.
It is also possible to "spoof" IP addresses to make the source of a connection look like it is coming from somewhere else. However, several of the offensive messages were made prior to the government IP addresses being disclosed in 2008.
Government machines were also used to vandalise, or "troll", on several pages, including:In the entry about indie band The Libertines: "[T]he more astute critics correctly identify the band as scum", and added a remark about lead singer Pete Doherty's drug use. Comments about footballer Wayne Rooney that said he was "currently knocking off 'queen chav' Coleen McGlochlin". The deletion of the entire post for Irish politician Christopher Byrne, replacing it with simply "is a sexy beast". Changing the entry for BBC presenter Peter Levy to list "Adolf Hitler" as an ex-partner. Describing Arsenal manager Arsene Wenger as being "made of clay".
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