- The woman, 27, was arrested after landing in Heathrow on a flight from Ethiopia
- Thought to be the first case of a returning mother whose child was born into ISIS
- MI5 previously said around 850 extremists from Britain travelled to Middle East
- As ISIS flushed out, UK counter-terror police bracing itself for jihadi bride influx
A suspected jihadi bride who returned to the UK having given birth to a child under Islamic State rule in Syria has been bailed after she was arrested at Heathrow.
The woman, 27, whose identity has not been revealed arrived on a flight from Addis Ababa and was arrested on suspicion of preparation of terrorist acts under section 5 of the Terrorist Act 2006.
It is thought this is the first case of its kind involving a mother and a child born into the ISIS regime.
MI5 has previously said around 850 extremists from Britain travelled to the Middle East as ISIS took control of pockets of Syria and Iraq.
And as the terror group is flushed out of its former strongholds, many of its militants with British passports are returning home with their families.
The mother is the latest in a string of arrests made by British counter-terror police bracing itself for an influx of jihadi brides.
Among the blacklisted British citizens still thought to be living within ISIS territory are Omar Hussain, a former Morrisons supermarket security guard-turned jihadi recruiter from High Wycombe, Aqsa Mahmood (pictured), a Glaswegian who went to Syria to marry an ISIS fighter aged 20, and London-born Muslim convert Grace Dare, whose ISIS husband Abu Bakr has since been killed
The child, who is younger than two-year-old, has been taken into care, according to the Sunday Times.
It is understood the woman flew from Ethiopia in an attempt to cover her tracks, but counter-terror officers were waiting at the airport for her when she landed.
A Metropolitan Police spokesman said: 'She was detained under PACE and taken to a south London police station, where she currently remains in police custody.'
While the inquiry continues, the boy has been taken into care as counter-terror police continue to crack down on Britain-bound terrorists.
Last year, ministers stripped more than 150 jihadists of their citizenship and banned them from Britain, as intelligence chiefs warned they may return from war-torn Syria and unleash a new wave of attacks.
Many of those returning were trained in the use of explosives and firearms as they took part in ISIS's bloody rampage.
Time is running out for the government to act before ISIS falls, as it can only strip citizenship of those who will not be left stateless.
In May, security sources said around 350 ISIS fighters had already come back to the UK from Syria and estimate another 300 could yet return.
Among the blacklisted British citizens still thought to be living within ISIS territory are Omar Hussain, a former Morrisons supermarket security guard-turned jihadi recruiter from High Wycombe, Aqsa Mahmood, a Glaswegian who went to Syria to marry an ISIS fighter aged 20, and London-born Muslim convert Grace Dare, whose ISIS husband Abu Bakr has since been killed.
Former British punk rocker Sally Jones, 49, left her home with her son to join ISIS in Syria and is on the Pentagon's kill list.
She was killed in an airstrike in June but the future of her son Jojo, who appeared in ISIS' sick propaganda videos, is unclear.
In a tense interview this morning, Tania Joya (left) said she still loved her former husband John Georgelas (right), an American-born convert to Islam with whom she has four children
The British ex-wife of a top US ISIS member stunned Piers Morgan during a tense TV interview this week by admitting she still loves the jihadist and insisting he 'has a good side'.
Tania Joya became radicalised while growing up in Harrow, London, but now lives in Dallas, Texas after fleeing from the terror group and rejecting extremism.
But during a grilling on ITV's Good Morning Britain today, presenter Piers Morgan said he was 'struggling to understand' why she should not be considered a 'potentially dangerous person'.
The interview came to an abrupt end with the DailyMail.com US Editor-in-Chief and co-presenter Susanna Reid shaking their heads as the former jihadi bride admitted still loving ex-husband John Georgelas - an American-born convert to Islam with whom she has four children.
Joya said she was 'pretty sure' Georgelas was still fighting for ISIS in Syria but that he had given her 'four beautiful, lovely children' and insisted 'everybody has a good side, everybody has a bad side'.
British anti-terror police have stepped up arrests in the wake of three terror attacks in the UK last year.
On March 22, Khalid Masood killed five people when he ploughed a hire car into pedestrians on Westminster Bridge before launching a knife attack in the capital.
Just over two months later on June 3, a copycat attack on London Bridge claimed the lives of eight victims when Khuram Butt, Rachid Redouane and Youssef Zaghba used a van and knives to slaughter people in Borough Market.
It came days after Salman Abedi blew himself at Manchester Arena using a homemade bomb killing 22 Ariana Grande fans who were piling out of the venue on May 22.
A series of other terror plots, whose perpetrators travelled to the ISIS warzone have been thwarted, including that of so-called 'Surgeon' Tarik Hassane, who wanted to attack police.
ISIS is currently facing multiple offensives in both Iraq and Syria, with US-led airstrikes, Russian and Syrian forces as well as Kurdish and other groups pushing them back.