The government is drawing up a list of sites inadvertently blocked by the filters it asked internet service providers (ISPs) to implement.
Many sites on the list are run by charities that aim to educate children and others about health, sex education and drugs issues.
The whitelist will be used to ensure the sites are not immediately blocked.
The list has emerged from a working group looking into accidental blocking and how to fix the problem.
'Master list'
The group is also looking into ways to set up a standard system that will let any site which thinks it has been wrongly blocked tell ISPs about the mistake so it can get on to the approved list.UK ISP Site Filters: Government To Create Whitelist [bbc.co.uk]
[edited by: engine at 3:14 pm (utc) on Jan 31, 2014]