First spotted on Monday by Maiy Azize, an advisor for the Australian Greens, kevinrudd.com was blocked on parliament's network for all staff, displaying the message "access to this webpage is restricted at this time".

".@MrKRudd Fair shake of the sauce bottle! Your website has been blocked by parliament," Azize said in a tweet.

Fairfax Media asked parliament's Department of Parliamentary Services, which manages the computer network, why Mr Rudd's website was blocked.

A spokeswoman said the website was mistakenly blocked when the the vendor behind Parliament House's internet filter changed the classification of the website to "weapons" without notice.

Other content to do with illegal gambling and pornography is also blocked.

"The Department has manually fixed this and has restored access," the spokeswoman said on Tuesday. "The department has also asked the [filter] vendor to fix this categorisation error worldwide."

The spokeswoman added that classifications were determined by "automated scanners" — computer software that trawls the web and attempts to classify content without a human's intervention.

One clue as to why the website may have been blocked lies in the transcript of a speech Mr Rudd gave in New York earlier this month.

It talked of "new weapons of mass destruction in the form of cyber terrorism, cyber crime and state-based cyber attack against critical infrastructure" being a threat to international order.

The Department of Parliamentary Services uses web content filtering services to protect itself from cyber threats and to prevent users accessing content deemed inappropriate for the workplace.

But the filter has been a cause of frustration for members of parliament for some time now.

In 2008, Greens Senator Kerry Nettle complained about not being able to access the website of a gay and lesbian news website based in Sydney.

"It is a site we use regularly in our offices — one of the two main gay newspapers in Sydney," she said. "But it took a week to get that unblocked, and that was only because my staff kept following up with [the IT helpdesk] and eventually somebody called back who said they were from IT security and could arrange to have the site unblocked."

In another instance, Senator Nettle said she was blocked from accessing an article "on a hemp embassy website" when researching drug law reform.

"I looked up what the New South Wales government had just decided about the commercialisation of industrial hemp crops, which is the legislation they are dealing with now," she said.

"It came up with the category as 'illegal drugs' and I had to go to the event without being able to access information about a New South Wales government program."