The UK Border Agency has been condemned by MPs for causing chaos in the student visa system - meaning the number of migrants abusing the student route soared by as much as 50,000.
The Public Accounts Committee said it was "extraordinary" for UKBA to have introduced new requirements for students to have their visas sponsored by universities in 2009 without ensuring proper controls were in place.
Attempts to remedy the situation have left universities and other educational institutions saddled with additional bureaucracy as rule changes and new procedures filter into the system over the past three years, said the committee.
The Public Accounts Committee report follows news last week London Metropolitan University was being stripped of its licence to bring in students from outside the EU, leaving hundreds of legitimate students facing deportation if they can not find an alternative visa sponsor. The Home Office said it had found more than a quarter of the university's international students were not legitimate.
Public Accounts Committee chairwoman Margaret Hodge said: "The result of the UKBA's poorly planned and ill-thought out course of action was chaos: an immediate high level of abuse of the new system and a surge in the number of student visas. In 2009 the number of migrants who abused the student route to work rather than study went up by as much as 40,000 to 50,000."
Mrs Hodge said legitimate international students make a valuable contribution to the UK economy. She said the UKBA had a responsibility to reduce burdens on those who do come here to study. But she said UKBA had also been "unacceptably slow" to react to a surge in the number of people who abuse the student route in an attempt to come to Britain to work, not study.
The Labour MP said: "Even where it has been told by colleges that so-called students are not studying, it has been unacceptably slow to act. The UKBA must take urgent enforcement action to remove them. This would also send a message to other would-be migrants that the student route is not an easy option for those with no intention of studying."
Following its research, the committee said the Home Office, through UKBA, introduced Tier 4 of the Points Based System for student immigration in March 2009. It was intended to control the entry of students from outside the European Economic Area who come to the UK to study. Under Tier 4 of the system, students have to be sponsored by an educational institution which is licensed by UKBA.
Responsibility for testing whether applicants are likely to comply with their visa conditions has been transferred from the UKBA to the sponsoring institution. But the committee said UKBA implemented the new system before proper controls were in place and it removed the controls it relied on under the old system. These included intention testing and spot checks interview by entry officers at the border.
Additionally, the committee said the UKBA did not make its secure electronic system, which demonstrates a student has a licensed sponsor for their student visa, mandatory until February 2010, months after the revised visa rules came into force. The committee said the result was an additional 40,000 to 50,000 additional migrants coming to the UK to work rather than study.