More than 70 websites today published guidance to student protesters about avoiding arrest, in defiance of a police ruling that doing so was unlawful.

The anti-police blog Fitwatch was suspended yesterday after detectives from C011, the Metropolitan police's public order branch, told the company hosting its website that it was "being used to undertake criminal activities".

In a blogpost published hours earlier, Fitwatch gave advice about avoiding arrest to students involved in last week's protest at the Millbank headquarters of the Conservative party. Fitwatch was removed soon afterwards, but tonight the offending blogpost, which recommended that students "get rid" of clothes they wore at the demonstration and change their appearance, had been republished on an additional 78 websites, including Facebook.

Many of the websites republishing the material were run by political activists, who disseminated the material via Twitter in what they described as a campaign to show the futility of police censorship.

Fitwatch campaigners said they planned to get their original website rehosted within 36 hours, adding that it was also likely that they would republish the offending article.

In its original letter to Fitwatch's website hosting service – JustHost.com – the Met's e-crime unit asked the domain provider to suspend the website "for a minimum of 12 months". The letter, seen by the Guardian, said the guidance to student protesters was "attempting to pervert the course of justice" and "authority to close the website" had been given by an acting detective inspector. The Met said in a statement: "We were concerned this website was giving information about destroying evidence. We drew this to the attention of the internet infrastructure providers and they suspended the site."

The force declined to say whether it would take the same course of action against dozens of other websites that published a verbatim copy of the guidance.

A largely peaceful demonstration against the proposed increase in tuition fees turned violent last Wednesday when a minority of the 50,000 protesters targeted Millbank. Around 200 entered the building and some reached the roof. During a period of rioting, windows and furniture were smashed and, in the most serious act of violence, a fire extinguisher was thrown towards police from the roof.

More than 50 people have been arrested, including an 18-year-old questioned on suspicion of attempted murder for throwing the fire extinguisher. Yesterday police released CCTV images of an additional 13 people they wanted to question over the disturbances. The Daily Telegraph had previously launched its own campaign to identify student protesters, posting photographs of activists it suggested had been involved in criminal activity.

The Fitwatch blogpost was presented as a response to the Telegraph's initiative, which it described as an "irresponsible and frenzied shop-a-student" campaign. Issuing guidance to students who might be worried they would be identified, the blog suggested they consider getting rid of clothes, spray cans and "dodgy texts/photos on your phone". It also recommended changing appearance. "Perhaps now is a good time for a makeover," said the post. "Get a haircut and colour, grow a beard, wear glasses. It isn't a guarantee, but may help throw them off the scent."

It added: "The police often use the psychological pressure of knowing they have your picture to persuade you to 'come forward'. Unless you have a very pressing reason to do otherwise, let them come and find you, if they know who you are."

Fitwatch was set up in 2007 by protesters seeking to oppose what they saw as objectionable surveillance tactics used by Forward Intelligence Teams (Fits), who use cameras to monitor political activists. The site has proved controversial among public order police officers, who found their own names, badge numbers and photographs uploaded on the internet.