Minicab drivers in London will only be able to gain required qualifications at official centres after a cheating scandal was exposed by the BBC.
Drivers could previously sit mandatory exams at Transport for London (TfL) centres or authorised private schools and colleges to get a licence.
TfL said all licences gained from colleges where cheating occurred had been revoked.
As part of the cab application process, drivers must sit a topographical exam and an English test at one of eight official TfL testing centres.
Evidence of these exams can also be accepted via other qualifications including BTecs, which are usually taken at numerous private colleges and centres around the UK.
Some employees at one of these colleges - Vista Training Solutions in Newham, east London - offered to take the tests for several BBC researchers for £500 per BTec.
After the cheating was exposed, TfL carried out an "urgent review" of every licence gained through qualifications passed at private colleges.
It has now revoked those of 143 drivers who had gained them through Vista Training Solutions while another 209 licence applications made by people who passed their qualifications through the college have also been rejected.
The transport authority added that no evidence of "fraudulent activity" had been found at any other private colleges but from February, qualifications will only be allowed to be gained from one of TfL's eight testing centres.
"The most robust and relevant topographical tests are our own assessments," said Helen Chapman, TfL's director of licensing, regulation and charging.
In a statement Ofqual, which regulates tests taken at private colleges, said it took "all allegations of qualifications fraud extremely seriously".
Vista Training Solutions previously said it was "devastated to learn that such malpractice took place" and apologised "unreservedly".