A female British jihadist has condemned David Cameron for 'waging wars' against Muslims, saying she wants his 'head on a spike'.

The 18-year-old, who is believed to be living in the ISIS stronghold of Raqqa, north-east Syria, also hit out at the Prime Minister's plans to prevent British jihadis from re-entering the country.

She claimed she would not care if she was stripped of her UK citizenship, describing the notion as 'quite laughable'.

It comes amid concerns that a growing number of young women are leaving their families in Britain to join the jihadi cause in Syria.

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Threat: A female British jihadist has condemned David Cameron (right) for 'waging wars' against Muslims, saying she wants 'his head on a spike'. Left, the girl posted this chilling photo (left) on her Twitter profile

Post: Taking to Twitter, the 18-year-old wrote: 'In sha Allaha day will come when David Camerons head will be on a spike as he continues to wage war on the awilya of Allah... and strike terror in the hearts of the kuffar'

Taking to Twitter, the girl wrote: 'In sha Allah [God willing] a day will come when David Camerons head will be on a spike as he continues to wage war on the awilya [protectors] of Allah... and strike terror in the hearts of the kuffar.'

She added: 'I really do not understand why Britain is threatening to remove our citizenship like we care lool its actually quiet laughable (sic).'

Although the girl, who uses the handle @UmmKhattab_, has posted photos to the social networking site showing her wearing a niqab with a gun slung over her shoulder, she is yet to reveal her identity.

In recent weeks, she has also called for the black flag of ISIS to be raised over Downing Street and claimed she is 'excited' at the thought of U.S. soldiers being 'slayed' if an invasion took place.

Criticism: The girl, who is believed to be living in the ISIS stronghold of Raqqa, Syria, also hit out at the Prime Minister's plans to ban British jihadis from re-entering the country. She described them as 'quite laughable'

Encouragement: And she encouraged other Britons to travel to the war-torn country of Syria, saying: 'I might be only 18 but I know coming to shaam [is] the best decision. Staying in the UK completely diminishes your islam'

She has even encouraged other Britons to travel to Syria, saying: 'I might be only 18 but I know coming to shaam [is] the best decision. Staying in the UK completely diminishes your islam.'

The jihadist set up her Twitter account on June 27 - just one day after schoolgirl sisters Salma and Zahra Halane fled to Syria.

The 16-year-old twins, who have 28 GCSEs between them, ran away from their family in Chorlton, Greater Manchester, on June 26 for 'paradise' in the war-torn Middle East.

They have vowed never to return home after following their brother to Syria, and are said to have already married ISIS fighters.

Devastation: Syrians are pictured inspecting the rubble of a damaged houses and cars on Saturday following a Syrian government airstrike in the north-eastern city of Raqqa, which is an Islamic State stronghold

Recruits: The jihadist set up her Twitter account on June 27 - just one day after schoolgirl sisters Salma (right) and Zahra (left) Halane fled to Syria. The 16-year-old twins ran away from their family in Chorlton, Manchester

Yesterday, it was claimed that female British jihadis are operating a religious police force in Syria that punishes women for 'un-Islamic' behaviour.

The al-Khanssaa brigade is a female-only militia set up by the Islamic State in Raqqa, Syria, with a key figure believed to be Aqsa Mahmood, 20, of Glasgow, who fled to the country last year.

Academics at King's College London have identified three other British females as members of the group - and say there are about 60 UK women who have gone to Syria on jihad.

I really do not understand why Britain is threatening to remove our citizenship, like we care... it's actually quite laughable Female British jihadist

Most of these women - including privately-educated Mahmood - are aged between 18 and 24, with al-Khanssaa said to be seeking out people engaging in Western culture in Raqqa.

Melanie Smith, a research associate at King's College's International Centre for the Study of Radicalisation, told journalists Robert Mendick and Robert Verkaik of The Sunday Telegraph: ‘Al-Khanssaa is a sharia police brigade. This is Isil’s female law enforcement.

'We think it’s a mixture of British and French women but its social media accounts are run by the British and they are written in English.

‘Given how small the community networks are - we know there are about 500 male British jihadis out there - it is quite likely these women move in the same circles as the British killer of Foley and Sotloff.'

Among the British women currently waging jihad in Syria are the Halane twins, mother Khadijah Dare, 22, and Muslim convert Sally Jones, 45, from Chatham, Kent.

Jihadis: A key figure in the al-Khanssaa brigade is believed to be Aqsa Mahmood (right), 20, from Glasgow, while Sally Jones (left), 45, from Kent, claims to have joined jihadis roaming the border between Syria and Iraq

Earlier this month, Mr Cameron unveiled controversial new plans to crack down on jihadists bringing bloodshed to Britain’s streets.

He vowed to introduce measures to bar home-grown fanatics fighting in the Middle East from re-entering the UK, either by stripping them of their passports or stopping them boarding flights back home.