A report suggesting that more than 150,000 international students may have overstayed in the UK is "seriously misleading" according to language centre association English UK.

A report by the UKBA chief inspector of immigration, John Vine, says that there was a backlog of 152,000 notifications about changes in students' circumstances in May, which meant there could potentially have been "thousands" of migrants who were not complying with their visas and whose leave should have been curtailed by the agency, but had not been. Institutions sponsoring students must tell the Border Agency if students do not enrol, miss sessions, or have a "significant" change in their circumstances.

English UK's Chief executive Tony Millns says that it is a misinterpretation to assume that students reported under this system are overstaying, or even in the UK.

"Sponsors don't want bogus or overstaying students, so they are scrupulously reporting everything that the law requires. The trouble is that often the system itself is at fault -- for instance, if a student has a formal offer at two colleges, they will be reported as failing to enrol at the one they turn down. This report would brand that student as potentially overstaying, whereas they are studying perfectly legally at a different institution.

"It's clear that the Border Agency hasn't been pursuing most of these supposed 150,000 overstayers, because they know perfectly well that they don't exist."

Out of 152,000 students cited in the report as possibly overstaying in the UK:

• 62,000 were classified as having "significant changes in circumstances." This could mean transferring to a different course at the same institution, or that their study centre had moved. " It is generally not a reason to raise concerns that the students are either not genuine or potential overstayers," said Mr Millns

• A further 31,930 "failed to enrol on the course." This generally means that a student has applied for and been offered places at more than one institution. They can't go to both, but because of the way the system works the rejected college has to report the student as failing to enrol.

• A further 29,000 cases are where the sponsor has stopped sponsoring the student. "Again, in many cases this means that the student has decided to switch to another sponsor institution, as students do all the time."

• 16,000 cases were of "discontinued studies" -- which often means the student has decided to return home. The UK's border system means it is impossible to establish whether this has actually happened.

• In 11,000 cases the student had "missed 10 expected interactions" -- in other words, hadn't turned up for class. "Sponsors tend to use this as a final warning for students whose attendance is unsatisfactory, to get them back on track," said Mr Millns.

• Finally, just under 2,000 students "may have breached conditions of leave" -- usually used if sponsors think they may be worked without permission or for to many hours. "This doesn't necessarily correlate with overstaying -- it is likelier to mean that the student's funding hasn't arrived and they need to work more than they should," said Mr Millns.