Almost 100,000 pieces of terrorist or extremist content have been removed from the internet since 2010, the Government has disclosed.

The figure was disclosed in a briefing note issued to schools on how social media is being used to encourage travel to Syria and Iraq.

From today schools and other public bodies are required by statute to take steps to prevent people being drawn into terrorism.

The document said: "The Government and police work closely with the communications industry to remove extremist and terrorist content from the internet.

"Since February 2010, over 95,000 pieces of terrorist content have been removed from the internet."

Home Secretary Theresa May said last month that the Counter Terrorism Internet Referral Unit was removing material at a rate of around 1,000 a week.

The self-proclaimed Islamic State - also known as Isil - has established an extensive online propaganda network.

The briefing note, issued jointly by the Home Office and Department for Education said terrorist organisations including Isil are trying to radicalise and recruit young people through "an extensive use of social media and the internet".

It added: "As with other online harms, every teacher needs to be aware of the risks posed by the online activity of extremist and terrorist groups.

"Schools have a vital role to play in protecting pupils from the risks of extremism and radicalisation.

"Keeping children safe from risks posed by terrorist exploitation of social media should be approached in the same way as safeguarding children from any other online abuse."

The document set out the ways in which different social networks are used. It said:

:: Facebook is used by Isil supporters to share content such as news stories and YouTube videos among their peer groups.

:: Twitter is a popular social media platform for pro-Isil accounts.

:: YouTube is used to host videos, both of official Isil output and videos created by users themselves.

:: Ask.fm is sometimes used by those considering travelling to Syria or Iraq to ask British jihadis and female ISIL supporters about travel, living standards, recruitment, fighting and broader ideology.

:: Instagram is used by Isil supporters to show landscapes and images "suggesting they are living a full and happy life".

:: Tumblr is "exploited" by fighters to "promote longer, theological arguments for travel".

The briefing note stressed that the companies cited "continue to work with us to limit the abuse of their platforms by terrorists and their supporters.

However, it added: "More content is uploaded all the time by people from this country and elsewhere who have joined ISIL in Syria and Iraq."

Councils, prisons, NHS trusts and schools will be required to take action to stop people being drawn into terrorism under new rules introduced today.

Laws passed earlier this year place public bodies under a statutory duty to identify and report those vulnerable to radicalisation.