The arrest of 12 men, who were subsequently released without charge, at the start of the month over an alleged bomb plot has re-ignited concern over student visa checks here and abroad.
Once it emerged that ten of those arrested had entered the country from Pakistan on student visas, the Home Office was criticised for not applying more rigorous checks.
Mohammed Ayub, representing three of the men, said: “After 13 days in custody, during which no evidence of any wrongdoing was disclosed, they have now been released without charge.”
All but one of those arrested are Pakistani nationals who were transferred to the custody of the UK Borders Agency after being freed last week.
The prime minister's spokesperson said that they would try and deport the men, aged between 22 and 38, under grounds of national security.
Mr Ayub, a lawyer, said that his clients have every right to remain in Britain: “Our clients have no criminal history, they were here lawfully on student visas and all were pursuing their studies and working part-time. Our clients are neither extremists not terrorists.”
Shadow home secretary Chris Grayling said there were "serious concerns" over the current visa system: “Whilst we welcome the implementation of the points based system, the changes that came into effect this year do not solve the existing problems.
"We have warned for years about abuses of the student visa system for immigration purposes, as this route is often fraudulently used as a way into the UK.”
Mr Grayling said it was important to maintain a strong influx of foreign students but lamented the Home Office for failing to deal with consistent breaches.
The high profile raids, in Manchester, Liverpool and Lancashire, were pushed forward after anti terror chief Sir Bob Quit was photographed by journalists outside Downing Street with top secret documents.
One of the arrests took place at Liverpool’s John Moores University, where footage of a student being hurled to the ground was captured by a student inside the campus.
The police have said that photographs of four locations in Manchester were found during the searches. These were of two popular shopping centres, a nightclub and a busy city centre square.
On 31 March this year tighter student visa regulations came into place, linking visas to learning institutions, following the introduction of compulsory identity cards being for international students in December 2008.
Universities UK (UUK) insisted that the necessary checks were taken in granting student visas and refuted claims that universities were in any way unscrupulous.
A UUK spokesperson said: “Universities take the issue of national security very seriously. It is simply irresponsible for anyone to suggest, for example, that this issue is being ignored by universities for the sake of international student fees.”
For the past 18 months it has been mandatory for postgraduate students applying to study "sensitive" subjects like science and technology to be, initially, vetted by the government. Clearance then has to be granted by the government before the Home Office can consider applications.
UUK said that surveillance of many incoming students was taking place: “Once international students are here many are required to register with the police in their local area and provide the police with their contact details.”
Sir Bob Quit resigned the day following the arrests and remains entitled to his full final salary pension.