"Operators that use UK highways could be risking their own operator licences if they don't ensure that their drivers and vehicles comply with UK law," he said.
"Vehicle & Operator Services Agency (VOSA) officers have been issuing roadside penalties for a wide range of transport and traffic offences. These range between £30 and £200.
"Operators that accumulate penalty notices frequently are likely to be called to a public inquiry before a traffic commissioner," he added. The operator licence may be cut, suspended or revoked as a result, he said.