Eagle-eyed campaigners for freedom of speech claim to have spotted an attempt to slip a call for a Europe-wide ban on pornography into an otherwise-innocuous piece of EU paperwork.

On Tuesday, members of the European Parliament will vote on the worthy yet mundane-sounding Report on Eliminating Gender Stereotypes in the EU. But bloggers this week pounced on an article in the report that calls for “a ban on all forms of pornography in the media”, and urged their supporters to bombard all 754 MEPs with emails condemning the “unacceptable political invasion of people’s bedrooms”.

While Tuesday’s vote in Strasbourg is merely an expression of support and would not be legally binding, critics worry that it could be the first step towards draconian policing of the internet in Europe. It comes after Iceland began drafting legislation to ban all online pornography, prompting cries of censorship.

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Rickard Falkvinge, a founder of the libertarian Swedish Pirate Party, said the text coming before the European Parliament was a “horrendous attack on our fundamental freedoms of speech and expression” while a Pirate Party MEP, Christian Engstrom, warned that “the devil is in the detail” – in particular a call in the report for “a charter to which all internet operators will be invited to adhere”.

“This is quite clearly yet another attempt to get the internet service providers to start policing what citizens do on the internet, not by legislation, but by ‘self-regulation’,” he wrote on his blog. “This is something we have seen before in a number of different proposals, and which is one of the big threats against information freedom in our society.”

It seems their rallying cry for Europe’s inalienable right to look at porn struck a chord. Mr Engstrom said that by midday on Thursday he had received 350 emails urging MEPs to vote against the resolution – when they mysteriously stopped appearing in his inbox, prompting accusations that the European Parliament was blocking the emails.

Pouncing on the unfortunate timing of the controversy, Mr Engstrom wrote: “It appears that today, on International Women’s Day, the European Parliament is silently blocking all or most emails that contain the word ‘gender’.”

Parliamentary officials in Brussels, however, said an automatic spam filter was activated as soon as emails exceeded a certain level, to protect the institution from cyber attacks. They insisted that emails related to the gender report had not been singled out for quarantine.

The report was drafted by Kartika Tamara Liotard, a Dutch MEP, and aims to improve awareness of gender equality in the European Union – goals which Mr Engstrom conceded were “laudable”.

The report makes no distinction between different forms of “pornography in the media”, nor does it specify what media it is referring to. It is believed that at the vote on Tuesday MEPs are likely to amend the text to clarify that it is aimed at the use of pornography in advertising.

The report is not a piece of legislation, but such votes are often seen as testing grounds for ideas and proposals which could in future be put forward as European law.