The UK government is creating a whitelist of websites that have been inadvertently blocked by porn and anti-piracy filters implemented by internet service providers.

Several sites, such as those maintained by drug and sex education charities, have been blocked by over-enthusiastic filters introduced by the ISPs under governmental advice. The filters were introduced after the government called for a system to prevent children being exposed to pornography. And torrent listing sites, such as Pirate Bay and Kickass Torrents, have been blocked too.

The anti-porn filters are generally optional, and ISPs offer them to new customers during initial start-up. Anti-piracy filters are switched on at ISP level and cannot be removed.

A report by the BBC's Newsnight found in December that the adult content filters were also preventing access to sites that offer support services for people with sex addiction or sexual health and domestic abuse support sites.

TorrentFreak, the copyright and privacy news site, has also been said to have been blocked by the ISPs, presumably just because the word "torrent" is in its name.

The government will work with ISPs to find ways to ensure that those on the approved list are unblocked. "Research suggests the amount of inadvertent blocking is low. However. if you are a charity and you deal with teenagers in distress that matters to you," said David Miles, chairman of the group set up to deal with the issue.