Hundreds of taxi drivers have been granted licences despite declaring criminal convictions for sex offences, burglary and assault, figures show.
Six councils in north-west England granted or renewed permits for more than 300 convicted drivers since 2012.
The mother of a Salford student killed by a man posing as a taxi driver said it was “clearly wrong” to give licences to sex offenders.
MP Andrew Gwynne has called for current legislation to be tightened.
The Licensed Taxi Drivers Association (LTDA) said granting licences to convicted drivers was “putting the public at risk”.
A BBC investigation found one in five drivers applying for a taxi licence in the region over the last two years had a criminal record.