Ministers bid to block extremist videos posted on foreign websites
The government is attempting to block all online extremist videos that help to radicalise impressionable young men.
The Home Office is in talks with internet companies to refuse access to violent films that are hosted abroad.
The plans have been drawn up by James Brokenshire, the ex-security minister who was promoted to immigration minister after the resignation of Conservative colleague Mark Harper.
Ministers are keen to tackle the threat from jihadists in Syria.
One minister told the BBC that about 2,000 Europeans are thought to be fighting in Syria, including at least 200 known to the British security services.
It is feared that fighters returning to the UK will seek to radicalise young men in particular to launch terrorist attacks both at home and abroad.
Currently, the police and the Crown Prosecution Service can demand that videos posted on websites hosted in the UK be taken down.
Since February 2010, the Counter Terrorism Internet Referral Unit, or CTIRU, has taken down more than 21,000 pieces of illegal terrorist online content.
If the CTIRU and prosecutors deem material to be illegal it can be blocked from parts of the public sector, including schools and hospitals.
But this does not extend to domestic users - and filters can be turned off.
The BBC has also been told it has proved difficult for the government to act against sites hosted abroad, both in the Middle East and in the US, where freedom of speech is protected by the constitution.
"Through proposals from the extremism taskforce announced by the prime minister in November, we will look to further restrict access to material which is hosted overseas - but illegal under UK law - and help identify other harmful content to be included in family-friendly filters," James Brokenshire said.
The taskforce was set up to examine the government's strategy for dealing with extremism and radicalisation after the murder of the soldier Lee Rigby in Woolwich in south east London in 2013.
Mr Brokenshire added that the new controls could also be used to block access to images of child abuse online.
Last October, Prime Minister David Cameron condemned Facebook's decision to allow videos showing people being decapitated back on its pages.
He said it was "irresponsible" of the social network.
The Home Office also hopes it can also make it easier for people to report extremist content online.
Emma Carr, deputy director of campaign group Big Brother Watch, said: "Politicians and civil servants should not be deciding what we can see online. If content is to be blocked then it should be a court deciding that it is necessary and proportionate to do so.
"As people riot on the streets of Turkey over freedom of speech online and government censorship, this issue must be handled in a way that cannot be exploited by oppressive regimes around the world."