UK Border Agency has let thousands of overseas students overstay UK Border Agency staff have failed to check thousands of tip-offs about overseas students including whether they had actually enrolled on courses, a report has said. Thousands of overseas students have potentially been allowed to stay in Britain when they should have been asked to leave as a result of a fresh "significant failing" by the UK Border Agency. The UKBA chief inspector of immigration, John Vine, says at the time of his inspection in May there was a backlog of more than 150,000 notifications about changes in students' circumstances, including discontinuing, failing to enrol on their courses or breaching the conditions of their visas. In his report, published on Thursday, Vine says: "As a result, there could potentially be thousands of migrants in the UK who were not complying with the conditions of their visa and whose leave should have been curtailed by the agency but had not been. One senior manager informed us that at the time of the inspection there were potentially 26,000 students whose leave should have been curtailed and who should have had enforcement action taken against them. It is understood that the backlog of notifications about changes in the circumstances of overseas students dates back to March 2009. In May, UKBA launched Operation Mayapple to identify individuals who could still be in Britain but were not complying with their visa conditions. A team of staff in Sheffield analysed the outstanding notifications and showed that many infringements were minor such as a change of address. The chief inspector reports that for more serious notifications, which indicated that students were not complying with their leave conditions, the case was referred to the local immigration team for enforcement action. Operation Rosehip was launched by the at the same time to specifically target students who should no longer have been in Britain. UKBA said 23,000 students had been told to comply with their student visas or face enforcement action as a result. The immigration minister, Mark Harper, responded to the report saying: "We are the first government to tackle the historically high levels of abuse in the student visa system. We have toughened the rules to ensure that genuine students are not taken advantage of by organisations looking to sell immigration not education. At the same time, we have a great offer for the brightest and best international talent who want to study at our world class institutions. But Labour's Chris Bryant described it as yet another damning report about UKBA and said the existence of the 150,000-strong backlog was a scandalous situation.