CTIRU also compile a list of URLs for material hosted outside the UK which are blocked on networks of the public estate.
To date (as of December 2017), CTIRU is linked to the removal of 300,000 pieces of "illegal terrorist material" from the internet.
[1] The December 2013 report of the Prime Minister's Extremism Taskforce[2] said that it would "work with internet companies to restrict access to terrorist material online which is hosted overseas but illegal under UK law" and "work with the internet industry to help them in their continuing efforts to identify extremist content to include in family-friendly filters" which would likely involve lobbying ISPs to add the CTIRU list to their filters without the need for additional legislation.
CTIRU hold responsibility for the implementation of aspects of the Counter-Terrorism and Security Act 2015, and are the custodians of the CTIRU list - a continuously updated proscribed list of websites that is considered under the act to be illegal to access or attempt to access.
As of September 2016, all Schools, childcare facilities or organisations that provide care or facilities for children under the age of 18 in the UK, have a statutory duty to ensure their systems cannot be used to access any of these websites by using firewall technology or service providers that are members of the IWF (Internet Watch Foundation) and ensuring that the technology prevents access to sites featured on the CTIRU list.