One of four British jihadis hit by international sanctions has appeared to mock the move.

A post from a Twitter account thought to belong to Sally-Anne Jones taunted the Government after it was revealed that she was being made subject to a travel ban as part of attempts to stem the flow of Islamic State recruits.

The tweet referred to "laughing out loud" at the measure and finished with a smiley face symbol.

The post, made on an account under a version of a pseudonym linked to the 46-year-old, said: "Just found out from a article that David Cameron has put me on a UN Sanctions list as i lol @ England for giving me a travel ban :)"

In another tweet the user vowed to fight England "until my last breath". The ownership of the account has not been independently verified.

Jones and three other high-profile UK extremists have been added to a United Nations list and also face a freeze of their assets.

Analysts suggested the impact of the measures on their activities is likely to be limited.

Shashank Joshi, of security think-tank the Royal United Services Institute, said: "The way to view this is as a legal instrument.

"It is not going to particularly help with finding them or anything like that but it does make sure there are no legal loopholes if they seek to move around, if they try and travel back through Europe."

He added: "On the whole it does not change very much. You are still going to need intelligence agencies tracking them in the region, it won't change the basic level of threat."

Mr Joshi questioned how much of a deterrent impact the sanctions will have.

He said: "I think this is a very mild deterrent in the context of the momentous decision to go and join Islamic state. It is one tool in what has to be a very diverse tool box of counter-terrorism means."

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.

Hannah Stuart, an expert on terrorism at think-tank The Henry Jackson Society, said the development is "another example of the changing face" of the threat.

"These guys have only been in the public arena for 18 months to two years," she said.

She said policy in recent years has focused on preventing Britons from travelling and managing their return if they come back to the UK.

"I think this is a bit of a belated recognition from a policy point of view that a hardcore of British foreign fighters who don't want to return," she said.

Ms Stuart said financial sanctions and travel bans are "largely symbolic" for the named subjects because they are unlikely to attempt to access UK bank accounts or leave IS-controlled territory but may deter associates from helping them.