Some websites are blocked by the Commons authorities
MPs are prevented from surfing the internet for pornographic and other "inappropriate" material in their Commons offices, it has emerged.
A filter on the Commons IT system blocks access to websites that contain "offensive or illegal content or are sources of malicious software".
The policy emerged after an MP was unable to access colleague Lembit Opik's column on the Daily Sport site.
Mr Opik said he did not believe the site should be blocked.
"Because of the things they are trying to censor they may have made an assumption about this particular website," said Mr Opik.
But he said he did not believe the site was "inappropriate" and that although he backed the filters, which prevented MPs from being bombarded with "utter rubbish", he did think they were too restrictive and sometimes prevented MPs from accessing sites they needed for their work.
"It actually happens quite a lot," he said, adding: "Perhaps the filters can be finessed so that my words of wisdom can be shared by one and all in the Palace of Westminster."
Mr Opik said a Lib Dem colleague, Torbay MP Adrian Sanders, had brought the censorship of his Daily Sport column to his attention.
The Montgomeryshire MP has been writing a column for the Daily Sport, which describes itself as the "world's most outrageous newspaper", since last summer, and previously wrote for the paper in 2005.
The newspaper has come under fire for its sexually explicit content, with Labour MP Claire Curtis-Thomas last year unsuccessfully bidding to have it sold to adults only.
Guidance issued to all MPs in December 2007 warns MPs they have a duty to ensure the Parliamentary network is used properly "by themselves and their staff" and to avoid actions that "threaten the integrity of the system or bring it into disrepute".
Retained for year
It also offers advice on e-mail security and etiquette, including not to write any e-mails in capital letters "as it comes across as shouting" and to "be careful how you word e-mails as it easy for irony and jesting to be misinterpreted".
In a separate notice for Commons staff and MPs, they are warned against "knowingly accessing or transmitting e-mails, text, images or internet material which might reasonably be considered offensive, unless on official business".
The aim is to protect security but also to "help to prevent users of the network from being exposed to inappropriate material".
The web filtering system also "collects data related to user activity, including user names and all websites visited whether blocked or not and will be retained for a period of 12 months", it adds.
MPs who try to access sites deemed inappropriate are presented with a screen asking them to contact the Commons authorities for permission to view the material.
Those who break the rules face being disconnected from the system by the Serjeant-at-Arms.