It is preparing a number of prosecutions and is this week joining in Operation Fuschia to crack down on unlicensed labour being used in the daffodil fields of Cornwall.
A spokesman for the GLA said the body was working with immigration and benefits officers to identify use of unlicensed labour, which became illegal in November 2006. "We have done some interviews under caution and are taking steps towards possible prosecutions in May. We're also flagging down minibuses and checking occupants' details. We're pleased with the number of people who have come forward for licences."
However, nearly 250 applications have been refused and some operators are being probed further.
The procurator fiscal and Defra's legal team will decide if cases have merit, in Scotland and England respectively.