The Internet Watch Foundation (IWF) has denied involvement in blocking the Pirate Bay BitTorrent tracker site, after BT mobile broadband users were told they had fallen foul of a filter against "over 18 sites".

The users were told to visit the IWF website for more information on the block. The ISP industry body curates a blocklist of URLs where indecent images of children can be found.

The warning pointed users to a page on the IWF website for more information.

A spokeswoman for the organisation however said it had played no part in blocking the Pirate Bay. "We have no role regarding peer-to-peer traffic," she said, "nor legal content such as adult material and I'm afraid the IWF cannot answer why a blocked splash page for Pirate Bay would reference our organisation."

A spokesman for BT said it did not intend to imply the IWF had applied the block. "BT and the other UK mobile operators have agreed and implemented a voluntary Code of Practice for mobile content that restricts access to content unsuitable for customers under the age of 18," he said.

"The list of sites and content that is restricted is compiled by individual operators themselves. The warning that BT provides links to the IWF website for information on the Code only."

The page BT's warning linked to on the IWF website details a voluntary mobile industry code of practice on content regulation. It is not an IWF document however, but was published by O2, T-Mobile, Virgin Mobile, Orange, Vodafone and 3 in February 2004.

"The Code covers ­new types of content, including visual content, online gambling, mobile gaming, chat rooms and Internet access," it says.

BT's mobile broadband network is provided by Vodafone. Earlier this year the mobile operator also blamed its blocking of some Czech anti-censorship blogs on the IWF. They seemingly denied any involvement in that incident too.

The organisation is particularly sensitive to accusations of going beyond its remit after facing widespread criticism for blocking a Wikipedia page late last year. The action meant the encyclopedia's edit functions were inaccessible to a majority of UK internet users.

The four co-founders of the Pirate Bay were handed prison sentences and fine by a Swedish court last Friday, for copyright offences. ®

Related stories

• Barmy MPs want mandatory nanny filters - for the world (15 October 2009)
• IWF takes 'pragmatic' stance on level one images (10 September 2009)
• New web filter laws questioned by top child abuse cop (9 September 2009)
• Digital Britain Britain looks to export net censorship model to Europe (17 June 2009)
• Tories research increased net censorship (17 June 2009)
• Pirate-pursuing lawyers get DDo$ money transfer slap (12 May 2009)
• IWF: Child abuse domains down, reports up (29 April 2009)
• Pirate Bay judge and pro-copyright lobbyist accused of bias (23 April 2009)
• Old school music sales fell 8% last year (22 April 2009)
• BT blocks up to 40,000 child porn pages per day (7 April 2009)
• UK.gov to get power to force ISPs to block child porn (2 April 2009)
• Small ISPs reject call to filter out child abuse sites (25 February 2009)
• The IWF: Charity disparity? (20 February 2009)
• Belgium wants in on European web blocklist (23 January 2009)
• Demon ends porn-less Internet Archive block (16 January 2009)
• Germany pushes IWF-style child abuse blocklist (16 January 2009)
• Update IWF confirms Wayback Machine porn blacklisting (14 January 2009)
• Updated Brit porn filter censors 13 years of net history (14 January 2009)
• IWF rethinks its role (12 December 2008)
• IWF pulls Wikipedia from child porn blacklist (10 December 2008)
• Opinion Scorpions tale leaves IWF exposed (9 December 2008)
• Guest opinion Why the IWF was right to ban a Wikipedia page (9 December 2008)
• UK e-tailers scurry to scrap dodgy Heavy Metal covers (8 December 2008)
• Updated Brit ISPs censor Wikipedia over 'child porn' album cover (7 December 2008)