Four of the worst offenders - including a punk rocker and a supermarket worker - among British jihadis have been slapped with international sanctions by the United Nations.
The four terrorists - Omar Hussain from High Wycombe, Nasser Muthana from Cardiff, Aqsa Mahmood from Glasgow and Sally-Anne Jones from Chatham, in Kent - are suspected of leading recruitment drives and plotting terror attacks against the UK and elsewhere from strongholds in Syria, the Press Association reported.
The decision means the four are now subject to a global asset freeze and travel ban.
The move is also designed as a deterrent to dissuade would-be fighters.
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-Qaeda terrorists and extended to the self-proclaimed Islamic State terror group (also known as Isis, Isil or Daesh).
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.
A spokeswoman for Number 10 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.