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Pakistan has criticised Britain’s immigration system and offered to help with security checks on foreign students after it emerged that the majority of those arrested in connection with an alleged terror plot entered the country on student visas.

Gordon Brown yesterday pointed the finger at Pakistan, saying it needed to do more to stop suspected terrorists coming in to the UK. But Wajid Shamsul Hasan, the country's High Commissioner to the UK, hit back - saying Britain was not doing enough to prevent bogus applications for foreign student status. He added that Pakistani authorities could carry out background checks on those applying for student visas but were currently prevented from doing so.

Eleven of the 12 arrested in raids across the North West on Wednesday - including at Liverpool’s John Moores University - were Pakistani nationals, and 10 of them were in Britain on student visas.

The Prime Minister said: “We know that there are links between terrorists in Britain and terrorists in Pakistan. That is an important issue for us to follow through and that's why I will be talking to President Zardari about what Pakistan can do to help us in the future."

But Mr Shamsul Hasan said: “It's up to the British High Commission to explain how these people [the suspected terrorists] got through.

"It is at your end you have to do something more. Every day we are raiding people, we are arresting people, we are arresting suspects wherever we find them.”

Asked if there was a problem with the British system for visas, he replied: “Yes. If they allow us to make inquiries first, if they ask us to scrutinise those people who are seeking visas we can help them.

“But the thing is they have their own regime - the regime that vets these people. But unfortunately in every system certain mistakes are made."

"Bogus" colleges have enabled migrants from around the world to come to Britain by claiming that they are students on further education courses, or learning English. The absence of automatic interviews for every applicant for a visa has allowed bogus students, in turn, to escape proper scrutiny by British officials who issue the travel document overseas. There are up to 2,000 such "bogus" institutions in the UK, according to the Home Office.

Chris Grayling, Shadow Home Secretary, called for the Government to “urgently step up” background checks on students coming to Britain from countries linked to terror.

“The Government admits that student visas are a major loophole in our border controls,” he said. “Given these latest revelations we need to urgently step up monitoring of applications from parts of the world where we face terror issues.”

More than 42,000 student visas were issued to Pakistani students between 2004 and 2007 but it was only from this year that applications were checked against an expanded set of watch lists, including police and immigration databases.

In 2007-8, there were 9,544 student visas given out to Pakistani nationals. 98 per cent of applications for extension of leave to remain in Britain were granted in 2006.

Further weaknesses in the system were also exposed three years ago, when officers in Pakistan said that government targets meant it was “hit and miss” whether or not they spotted forged documents. In the same year, the British High Commission in Pakistan told the Home Affairs Select Committee they believed that about half the students to whom they granted visas disappeared after reaching Britain

A spokesman for the Home Office said all students applying to come to Britain are checked against terror “watch lists”.

“Every student wishing to study in the UK undergoes scrutiny - including fingerprint checks against a range of immigration, terrorism and crime watch lists,” he said.

“The Government will continue to welcome legitimate students who wish to receive a first-rate education, and we’ll do everything in our power to bar those who are up to no good.”

Sir Andrew Green, chairman of campaign group Migrationwatch UK, said student visas were a “gaping hole” in Britain’s borders.

“Applicants from countries of concern like Pakistan and North Africa should be given a full interview by a UK-based visa officer and only admitted if they can demonstrate that they are genuine."

New rules requiring colleges to be approved by the Government before they can bring students in were brought in last month. All foreign students now need to have a place on a course with a registered institution before they can come to Britain. But under the previous regime, which applies to foreign students currently in Britain, fewer checks were carried out.

Phil Woolas, Immigration Minister, admitted fake colleges were the “biggest loophole” in the immigration system when he introduced the new visa rules.

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