Police investigating the failed car bomb attacks on London's West End and Glasgow airport are holding eight people who were arrested in the UK and Australia. This is what is known so far about those who are being held:
DR BILAL ABDULLAH:
Iraqi doctor Bilal Talal Samad Abdullah was arrested at Glasgow Airport on Saturday following the failed car bombing.
He works at the Royal Alexandra Hospital in Paisley as a diabetes specialist.
Dr Bilal Abdullah was arrested at Glasgow Airport on Saturday...
Dr Abdullah qualified in Baghdad in 2004 and first registered as a doctor in the UK in 2006.
He was given limited registration by the General Medical Council (GMC) from 5 August 2006 to 11 August 2007.
Limited registration is awarded to recent medical graduates and it allowed him to work in Britain for a year, but in accordance with standard procedure, he could not move jobs during that time and had to be supervised.
He lives in Neuk Crescent, Houston, outside Glasgow.
The Guardian newspaper reported Dr Abdullah was born in Aylesbury, Buckinghamshire, where his father, also a doctor, worked.
After moving to Iraq, he studied at al-Mansour high school in Baghdad and later at Baghdad College, the paper said.
DR MOHAMMED ASHA:
A second doctor being held is Mohammed Asha, 26, who lives in Newcastle-under-Lyme, Staffordshire.
Dr Mohammed Asha has a two-year-old son...
He was arrested on the M6 motorway in Cheshire on Saturday night.
Dr Asha is of Palestinian descent but grew up in Jordan.
Dr Asha's father Jamil told the BBC that his son "never showed any signs of growing militancy" during his three-year stay in Britain and called his arrest a "mistake".
He said they "were in phone contact every week" and that his son had been due to visit on July 12 with his wife and their son.
Dr Azmi Mahafzah, who taught Dr Asha at the University of Jordan's medical school for six years, said he was a brilliant student, adding: "I can't even remotely imagine him being involved in extremist activities or terrorism."
Dr Asha won a scholarship to the Jubilee School for gifted children in the Jordanian capital, Amman.
Dr Aseel al-Omari, who described herself as a "close friend" of Dr Asha's, attended the same secondary school. She told the BBC: "I remember him as a liberal thinker who respected other nationalities and religions - that's what we were educated in our schools and in our career as doctors."
Security officials in Amman told the BBC that Dr Asha has no previous criminal record in Jordan.
Several newspapers have said he is one of eight children - six brothers and two sisters - three of whom are doctors and one an engineer.
Dr Asha spent his post-qualification year at the Royal Shrewsbury Hospital and the Princess Royal Hospital in Telford.
Dr Asha's mother Fawzia says her family rejects terrorism...
He then moved to the University Hospital of North Staffordshire in Stoke-on-Trent where he works as a neurologist.
Dr Asha is married with a young son and lives with his family in Sunningdale Grove in Newcastle-under-Lyme.
His wife was arrested with him on the M6 and both are being questioned at Paddington Green police station in London.
Dr Asha is believed to have completed an eight-week placement at the city's Addenbrooke's Hospital.
MARWAH DANA ASHA:
Marwah Dana Asha, the 27-year-old wife of Mohammed Asha, is reported by AFP to be a fellow Palestinian who was trained as a laboratory researcher.
She is the mother of a two-year-old boy.
Dr Asha's father told the AFP news agency that his son and his wife had met at school and married in 2004.
According to Jubilee School records, both had "exceptional records, exemplary social conduct and excellent academic results".
Marwah Dana Asha is trained as a laboratory researcher...
Mrs Asha later studied at the public University of Science and Technology in Jordan's northern city of Irbid, Mr Asha said.
Her mother, Um Abed, told AFP said she was deeply worried about her daughter.
"We are stunned," she said.
"Marwah and Mohammed are not the type who would be interested in political Islam."
Mrs Asha has three brothers and one sister, AFP says.
DR MOHAMMED HANEEF:
The man arrested at Brisbane Airport has been identified as Dr Mohammed Haneef, aged 27.
An Indian national, he was detained while trying to board a plane to India with a one-way ticket.
Dr Haneef studied medicine at the Rajiv Gandhi University of Health Sciences in Bangalore between 1997 to 2002, achieving a second-class degree.
His family come from a small town 250km outside Bangalore and his late father was a teacher.
His cousins are Sabeel and Kafeel Ahmed.
Dr Mohammed Haneef is the cousin of Sabeel and Kafeel Ahmed...
Queensland state leader Peter Beattie confirmed that the detained man had been working as a senior house officer at the Gold Coast Hospital since September 2006.
Before that, he worked at Halton Hospital in Cheshire.
The man answered an advert in the British Medical Journal in March 2006 for a job in Australia, Mr Beattie said.
Colleagues at the Gold Coast Hospital regarded him as "a model citizen with excellent references," he added.
The Times said he moved to the Gold Coast with his wife, living in an apartment building a couple of blocks from the hospital.
Steve Bosher, the manager of the apartment block, told the Sydney Morning Herald Dr Haneef's wife had returned to India earlier this year.
"He was a good tenant, always paying his rent on time and getting home at about 5.30pm," Mr Bosher said.
"I never saw him with anyone, he was very quiet. He was a young doctor at the hospital."
Dr Haneef was employed under Australia's temporary skilled worker scheme.
Dr Haneef's mother Qurat-ul-ain (left) says he is innocent...
His sister, Sumayya, told the Associated Press that her brother had been trying to return to India to see his daughter who was born on 26 June.
And she told The Australian newspaper: "His character is like a mirror - clean."
The agency also learned from his mother, Qurat-ul-ain, that Dr Haneef was raised in the Karnataka state town of Moodigere, but his family now lives in an affluent area of Bangalore where they moved after his father died 10 years ago.
The second man arrested at Glasgow Airport on Saturday has been named as Kafeel Ahmed.
The 27-year-old, from Bangalore, India, was one of two men arrested at the airport after a burning car was driven into the terminal building.
He suffered burns to 90% of his body and has been transferred to a specialist burns unit at Glasgow Royal Infirmary from a hospital in Paisley. He has been kept under armed guard and was described by health officials as still being in a critical condition.
It emerged that contrary to earlier reports, Mr Ahmed was not a medic but an engineer with a PhD in design and technology.
It is understood he began his studies at Queen's University, Belfast, in 2001 and remained in Northern Ireland until 2004.
It is believed he lived in rented accommodation in Hampton Place, close to the university.
A spokesman for Queen's University said officials were unable to comment.
He studied for his PhD in the department of design and technology at Anglia Polytechnic University (now called Anglia Rushkin University) in Cambridge, it is believed.
A spokeswoman for the university said it was co-operating fully with police inquiries, adding: "At this time identities are still unclear and it would be therefore inappropriate to comment further."
Mr Ahmed is thought to have returned to Bangalore in August 2005.
His brother is Dr Sabeel Ahmed.
DR SABEEL AHMED:
Dr Sabeel Ahmed, 26, was arrested near Liverpool's Lime Street station on Saturday night.
The BBC has learned that he is currently working at Warrington hospital but has also worked at Halton - both are part of North Cheshire NHS trust.
Dr Zakia Ahmed said her son was renewing his UK visa
He is from Bangalore in India and trained as a doctor at the city's Rajiv Gandhi University of Health Sciences - the same place Mohammed Haneef who was arrested in Brisbane trained. He qualified in 2005.
Dr Sabeel's parents are also both doctors and live in an affluent neighbourhood in Bangalore.
His mother, Dr Zakia Ahmed, has told the BBC that her son is second cousin to Dr Haneef.
And she said her son followed Dr Haneef to Britain to work.
His mother also said her son last visited his family in May this year.
She said she learned of his arrest through friends and has been able to speak to him briefly since he was detained.
She said her son was reapplying for his UK visa because he was hoping to do a post-graduate course.
Dr Sabeel Ahmed is the brother of Kafeel, arrested in Glasgow
"He calls me everyday", Dr Ahmed said, and "only talks about his patients and how his day went. As fellow doctors that's the only thing we talk about.
"This is all a mistake - he is innocent."
Dr Sabeel is being questioned at Paddington Green.
A 28-year-old man was arrested in Paisley on Sunday.
Several media reports say that he is a medical student or doctor working at the Royal Alexandra Hospital but officials have not confirmed this.
A 25-year-old man was also arrested in Paisley on Sunday. There are unconfirmed media reports that he too is a medical student or doctor at the same hospital.