Image copyright Other Image caption Mohammed Fakhri Al-Khabass began his studies in Khartoum in 2008

A British medic recruited at least 16 fellow students from the UK to join the Islamic State group, a BBC investigation has found.

Mohammed Fakhri Al-Khabass, from Middlesbrough, was said by his university to have "played a major role" in persuading two groups of Britons to head to Syria this year.

The students were recruited in Sudan where Mr Fakhri had studied.

They are the single largest UK group known to have joined IS militants.

Mr Fakhri is a British Palestinian who grew up in north-east England with his two older brothers. His father worked as an NHS doctor on Teesside.

He started his medical studies at the University of Medical Sciences and Technology (UMST) in Khartoum in 2008.

By 2011 he was president of the University's Islamic Cultural Association (ICA) which became much more radical under his leadership.

A number of students and ex-students at UMST - speaking to the BBC on condition of anonymity - said Mr Fakhri used his role within the ICA to spread a highly-politicised version of Islam. Ultimately, he started dissuading people from pursuing careers in the West.

UMST says Mr Fakhri is now in Syria but one of his brothers has said he believes he is still in Sudan.

His family turned down requests for an interview. However, his father Fakhri Al-Khabass later told journalists his son had brought shame on the family.

'Good intentions'

Image copyright Other Image caption Eight of the nine medics who travelled in March to Syria from Sudan, where they had studied

Most of the British students at UMST were the children of British-Sudanese parents who are successful UK doctors.

They had sent their children to Khartoum to study medicine because they wanted them to reconnect with their African and Islamic roots, before returning to work as doctors in Britain.

Nine British-Sudanese students and recent graduates disappeared from Khartoum in March, flying to Turkey, and then crossing over to Syria. Seven more followed in June, although two were detained in Turkey and returned to Khartoum.

"Mohammed Fakhri is in Syria and played a major role in recruiting the students who left to [go to] Turkey," said UMST dean Dr Ahmed Babiker Mohamed Zein.

The BBC understands that Mr Fakhri interrupted his studies to spend time in Syria but was able to resume his course when he returned.

One senior student suggested Mr Fakhri had tricked the pupils.

"He used to tell them that you will be serving as doctors on the Turkey-Syrian border and under the name of Islamic State. That's what the students who came back said.

"Until they went and were brought back, they didn't know they were going to any political side in the Syrian war. He used their good intentions."

Two British students who returned - Zubieda Widaa and Ahmed Abdoun - were allowed to resume their studies but were later expelled.

'Brainwashed'

Many of ICA's meetings were uncontroversial, but there are reports it held closed meetings off campus to show harrowing footage of victims of the Syrian regime's bombing of civilians.

Ahmed Sami Khider was one of the Britons targeted. A former student of Wallington County Grammar School in south London and the son of a doctor, he finished his UMST medical degree in July 2014.

One female contemporary described him as "decent, smart, cool and outgoing - never the kind of person who would be speaking or encouraging the idea of jihad or terrorism".

Facebook photographs show a young man having fun. But a source told the BBC he changed in the last year and "withdrew socially a bit".

Image copyright Other Image caption Ahmed Sami Khider appears in the IS recruitment video

Image copyright Other Image caption Mr Khider can be seen teaching other students in Syria in one clip

The next time she saw Mr Khider was in an IS propaganda video released in May, two months after he disappeared with his younger sister Nada.

IS films usually show pictures of masked men posing with guns. This time a softly spoken man was appealing for fellow UK doctors to join him in building a new society.

Sitting behind a desk in a wood-panelled office with a stethoscope around his neck, Mr Khider was serious and subdued.

He said: "There is a really good medical service being provided here, lots of hospitals… paediatric hospitals, with specialised doctors."

At this stage of his career he would normally be a junior doctor. In the film, which shows glossy wards, an MRI scanner and babies in incubators, he is seen teaching students.

He finally addresses the camera, saying: "Dear brothers and sisters, we as Muslims and as doctors have a great responsibility.

"All you are doing is sitting in the West in the comfort of your homes. Use your skills and come here."

His former friend was shocked, saying: "He looked like he was brainwashed or was talking through someone else."

Foreign Office intervention

Just weeks after the video emerged, the second batch of British medical students left Khartoum for Syria.

They include Mohammed and Ibrahim Ageed, whose father is an Accident and Emergency consultant in Leicestershire. One of their friends said the brothers were "the most kind-hearted, soft, polite, humble people I've met".

The families are reluctant to attract publicity but, talking anonymously or through intermediaries, they have made it clear they are angry with Mr Fakhri.

Image caption Brothers Mohamed (left) and Ibrahim (right) Ageed were among the seven students to leave for Syria in June

Many also feel UMST has failed in its duty by not providing enough pastoral care or extra-curricular activities.

One family member said of the university: "Its lacklustre attitude in student care, social activities and attention is as much at fault here."

UMST disputes such an impression, saying it has worked hard to eliminate radicalisation on campus. But the UK Foreign Office is now working with UMST and other universities in Khartoum to prevent further problems.

According to Manni Adbel Karim Ibrahim, a British-Sudanese youth worker in London, western Muslim students are particularly vulnerable to IS recruiters.

He says: "If you don't understand Islam and you don't know the answer to the questions or points they're putting to you... you can easily be taken in by what they say."

Meanwhile, another ex-UMST student warned the issue of people heading to Syria was only one part of the problem.

"From what I've heard there are IS supporters who have not left, and intend on coming back to the UK to work with the NHS - for whatever reason. "