The Government said last week that 1,050 language colleges have been investigated so far as part of a massive investigation into alleged bogus practices.
Des Browne, the Home Office minister responsible for immigration matters across the UK, said a quarter were found to be illegal fronts for bringing foreign nationals into the UK.
A further 25 per cent are said to require further investigation by immigration officials.
Most of the language schools investigated so far are in London, although the Home Office has pledged to widen its net across the UK. One organisation advertising overseas as a school was found to be a fish and chip shop. Another address investigated turned out to be a stonemason.
The Government announced earlier this year that a national register will regulate the industry.
Under the new rules, language colleges will need to prove they are registered companies and have been set up to offer legitimate courses. Only people entering the UK to take courses registered with the Department for Education and Skills will be granted a visa. Colleges will not have to pay to be placed on the register but the Home Office says they will face spot checks if there is any doubt that they are genuine.
The Government said bureaucracy would be kept to a minimum and any organisation receiving public funding, or those accredited by existing bodies, will automatically be entered on the register.
Answering questions in the Commons, Mr Browne said more "risk assessment units" would be set up in British embassies to improve the flow of intelligence.
But Tony Millns, chief executive of English UK, the country's largest accreditation body and representative organisation for language schools, said the new measures did not go far enough. They should include an inspection system to ensure schools carry on abiding by the rules. "It is not a perfect system but it is a lot better than nothing at all," Mr Millns said. "It has been a national scandal that there was absolutely no restriction on someone setting themselves up and claiming to be a language school when they were nothing of the sort."
The Home Office hopes to investigate another 150 language colleges by December. However, Mr Millns said there were fears that as many as 5,000 bogus language schools are currently operating.