Some of the most notorious British jihadis have been hit with international sanctions in a bid by the Government to stem the flow of home-grown Islamic State recruits.
Four men and women suspected of leading recruitment drives and plotting terror attacks against the UK and elsewhere from strongholds in Syria have been added to a United Nations list.
The four are Omar Hussain from High Wycombe, Nasser Muthana from Cardiff, Aqsa Mahmood from Glasgow and Sally-Anne Jones from Chatham, in Kent.
It is the first time the UK has submitted the names of the worst offenders among the around 700 thought to have travelled out to the region to join the Islamist extremists.
Some are believed to be holed-up in the extremist-held Syrian city of Raqqa - where two militants were killed in an RAF drone strike in August.
Jones travelled to Syria in 2013 with her husband Junaid Hussain who was killed in a US air strike in August. She uses social media to recruit women to join IS.
Mahmood went to Syria to join IS in 2013 and is thought to be a key figure in the al-Khanssaa brigade, a female brigade in Raqqa which was established by IS to enforce Sharia law. She has used social media to recruit and support IS.
Hussain, who is also known as Abu-Said al-Britani, travelled to Syria last year and also uses social media to recruit others to join IS.
Muthana joined IS in Syria in 2013 and has appeared in propaganda and recruitment videos. He has also threatened the UK in social media posts.
Approval by a UN committee means the group are subject to a global asset freeze and travel ban, but the move is also designed as a deterrent to dissuade would-be fighters.
One of five names submitted by the UK to the sanctions committee is still to be approved.
More are expected to be put forward.
It is the first time since 2006 that the UK has sought to place its own nationals under the United Nations sanctions regime set up to tackle suspected al Qaida terrorists and extended to IS.
Detailed dossiers of evidence were submitted to show they were "participating in the financing, planning, facilitating, preparing, or perpetrating of acts or activities" related to IS.
Uploading bomb-making instructions to social media was among the activities.
The Government is also stepping up its attention on the threat posed by IS, with Prime Minister David Cameron due next month to chair the first session of a dedicated sub-committee of the National Security Committee.
It will bring together senior ministers and defence and intelligence chiefs and would, an official said, inject "a bit more time and effort into the issue".
The move was revealed as Mr Cameron prepared to unveil a new £10 million UK-run counter-propaganda drive to blunt the effective use of social media by IS to spread its message.
He will set out the plans at a meeting in New York of allies in the fight against the extremist threat, which will involve US President Barack Obama and other key leaders.
IS, which is also known as ISIL, has proved deft at exploiting online channels using slick videos to spread its message.
The fightback will be carried out partly from a new unit set up jointly by the US in Abu Dhabi.
A No10 spokeswoman said: "The Prime Minister has been absolutely clear that we will do all we can to stop British citizens from going to fight for ISIL and that foreign fighters should face consequences for their actions.
"As well as the domestic measures we have introduced, such as the power to seize passports, these sanctions are a powerful tool - freezing an individual's assets and imposing a global travel ban on them.
"It also sends a clear deterrent message to those thinking of going to fight for ISIL. We will continue to consider whether more individuals should be subjected to these sanctions."
Three British nationals were already among the 231 individuals and 72 organisations on the UN list.