Home Secretary Theresa May has suggested three British schoolgirls believed to have escaped the clutches of ISIS may not be allowed back into the UK even if they manage to return.

Reports from Iraq suggest three teenagers who had been married off to ISIS fighters have now gone on the run near the city of Mosul.

It has been suggested the trio may be Shamima Begum, Amira Abase and Kadiza Sultana, who disappeared from their homes in east London earlier this year.

The newly-reappointed Mrs May today declined to say whether the girls would be allowed back into Britain even if they managed to escape the war-torn region.

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Escape: Three 'jihadi brides' are said to have escaped from their husbands in Mosul, according to a source -leading to speculation it could be the three classmates from east London, who ran away in February

Theresa May today said the government would examine their case if they managed to return to Britain

Asked about reports that the teenage girls have gone missing in Iraq after being married to militants from the group, Mrs May would say only that attempts to return are dealt with on a 'case-by-case' basis.

Mrs May told ITV1's Good Morning Britain: 'Obviously there are young people who go to Syria, some of whom find that what they see there is not what they thought it was going to be.

'We look on a case-by-case basis, and people have come back - youngsters who have gone there and suddenly realise what a mistake they've made.'

She confirmed that some young Britons who went to Syria or Iraq to join ISIS have come back after becoming disillusioned.

The exact identity of the girls and their fate is not known, but their reported ages match those of the three friends from east London, who ran away to join ISIS in February.

Shamima Begum, Amira Abase and Kadiza Sultana - who were all pupils at Bethnal Green Academy - flew to Turkey together, before crossing the border into war-torn Syria earlier this year.

It is understood they were following Sharmeena Begum, another friend who travelled there in December.

Identity?: They are thought be about 16 - the same age as Londoners Kadiza Sultana (left), Shamima Begum (right) and Amira Abase (below), who ran away from home in February of this year to join ISIS as brides

Unverified: However, just a couple of weeks ago Amira, pictured last September, tweeted from inside the Islamic State for the first time - and seemed to be enjoying herself, eating a takeaway with a friend

Mosul Eye, a blogger in Iraq, revealed the girls had fled on May 2 through his Facebook page - set up 'to communicate what's happening in Mosul to the rest of the world, minute by minute from an independent historian inside Mosul'.

'Three girls, (Foreigners - British) married to ISIL militants, reported missing, and ISIL announced to all its check points to search for them. It is believed that those girls have escaped,' he wrote.

FATHER OF FIRST RUNAWAY GIRL SAYS 'I HOPE MY GIRL HAS FLED' The father of the first east London schoolgirl to run away to Syria says he hopes his daughter is among those who have now fled ISIS. Sharmeena Uddin disappeared last December, before the other three schoolgirls, and was originally believed to be in the terrorist stronghold of Raqqa. Last night, her distraught father, Mohammed Uddin (pictured, below), said he hoped his 15-year-old daughter was among the trio now thought to have fled the barbaric terrorist group. Speaking from his East London home, Mr Uddin, 38, said police are examining the reports. 'I hope that it is Sharmeena because she's 16 at the end of the month. Maybe it's her. I hope it is,' he added. Advertisement

The blogger, who opposes ISIS and remains anonymous, has written in detail in both English and Arabic about the inner-workings of the group, their execution of civilians and casualties they suffer from coalition air-strikes.

In a later post he added: 'The latest info I got on them is they are still on the run, but still in Mosul, and ISIL is thoroughly searching for them and hasn't captured them yet.

'They are Brits, not immigrants, and they are very young teens (around 16 years old). That's all I have about them for now.'

At this time, Mosul Eye appears to be the only source reporting the girls' flight.

The blogger said on Tuesday evening - 10 days after the original post - that he was still unaware of their identities.

He said he didn't know what had happened to them after the initial search.

'We cannot confirm, as of yet, if those girls were the same trio mentioned in the British media, as their identities still unknown to us,' he wrote.

The Foreign Office was investigating who the trio might be, however.

A spokesman told the MailOnline: 'We are aware of reports and are looking into them.'

In earlier postings Mosul Eye warns of IS carrying out mass searches of homes, looking for laptops, mobile phones, tablets and other devices, warning: 'Please delete all your browsing history from anything related to politics, ISI, adult content, music, movies, pro-government pages.

'Please spread this around. We might go MIA for a few days until this is over.'

IS are reportedly unpopular with much of the local population and appear to be increasing the terror in the city as their losses mount.

In his latest postings, on May 7, the historian behind Mosul Eye talks of IS militants plundering money from locals, whipping a young man 60 times for not closing his shop during prayer time and the public executions of civilians for minor transgressions of Sharia law.

Possibilities: Salma (left) and Zahra Halane (right), of Greater Manchester, are among the other teenagers known to have gone to Syria to become jihadi brides, and could also be among the girls on the run

Content: This tweet, sent in April, suggested Amira was enjoying her new life in the Middle East

Normal teen: As Amira's Twitter account has become public, it also gives an insight into her life as a normal 15-year-old girl in East London, posting about shoes, waffles, sunsets and Chelsea FC

He also details increasing casualties for IS from coalition air-strikes.

However, the only public communication to have come from the three east London teenagers seems to suggest they are happy in their new lives.

Amira posted an online photo of her enjoying a takeaway dinner with another teenage 'jihadi bride' just over a fortnight ago.

It shows a huge Western-style takeaway, including fried chicken, chips, pizza and kebab meat.

Amira - tweeting under the name Bintt Abbas - captioned the photograph 'dawla takeaway w/ @um_ayoub12'. 'Dawla' is another name for the Islamic State, which is also known as Isis.

In March a High Court judge confiscated the passports of four other pupils at the school after concerns were raised by Tower Hamlets Council.

There are among around 600 people from the UK who have reportedly gone to join the extremists in Syrian and Iraq.

Among the 600 are a number of young girls - including the so-called 'terror twins' Salma and Zahra Halane, 16, from Chorlton, who travelled to Syria last July.

A few months later, Yusra Hussein, of Easton, in Bristol, also travelled to Syria, rumoured to be in the company of a 17-year-old from London.