Eight colleges in Tower Hamlets are being investigated so far by the Home Office amid claims that foreign students are cheating in English language tests to extend their UK visas.
Since 2011, applicants for UK Tier 4 student visas have been required to pass an English test before they can be awarded their visa.
Out of 48,000 English language certificates found to have been fraudulently obtained across the country, 29,000 results were invalid and 19,000 “questionable”.
So far, 8 out of 57 private colleges that were suspended were based in Tower Hamlets alone.
The probe followed a BBC Panorama investigation earlier this year which exposed systematic cheating in tests taking place at ETS test centres.
Undercover investigators for the BBC found that invigilators in the test centres read out answers to the whole exam room.
In a statement to the House of Commons on 24 June, immigration minister James Brokenshire claimed that the figure of fake certificates obtained is likely to be much higher as the investigation continues.
He added: “We will not hesitate to take firm action against those – students, colleges and universities – who do not abide by their legal responsibilities and resolutely pursue organised criminality to bring those responsible to justice.”
The National Crime Agency has been called in to assist the investigation and some arrests have already been made.
In a previous crackdown on bogus education in 2008, the Trading Standards estimated that there were up to 60 bogus colleges operating in the East London borough of Tower Hamlets alone.
The investigation still continues in London and other parts of the country.