HUNDREDS of truck drivers and motorcyclists given licences by a company embroiled in Victoria's largest bribes-for-licences scandal remain on the nation's roads, potentially posing a risk to other drivers.

VicRoads is retesting up to 940 drivers possibly ensnared in the scandal to see if they should be taken off the roads, and has appointed a former top-ranking policeman to review its outsourcing of truck and motorcycle licensing.

VicRoads and police are yet to determine the full extent of the alleged scam, after detectives charged the managers of a driving instruction company late last year with taking bribes in exchange for truck and motorcycle licences.

The VicRoads-accredited company, Mark's Driving School, operated out of Mildura and Melbourne and was run by a police officer and her husband. Both have been charged with 44 counts of receiving secret commissions, and further charges are expected.