The Gangmasters Licensing Authority carried out an unannounced inspection of firms around Spalding in the flower, plant and bulb industry to target worker abuse in the run-up to the peak Mother's Day and Easter period.


The authority, which regulates people who provide labour in the agriculture, horticulture and food processing and packaging sectors, interviewed workers, looked at the vehicles used to transport them and inspected nurseries.


Thirteen licensed gangmasters operating in the area are now under investigation after officers found cases of workers not being paid the agricultural minimum wage, not receiving holiday pay and being charged for accommodation without being given work.


They also found people transported to work sitting on a plank of wood held up by breeze blocks in the back of a van.


GLA chairman Paul Whitehouse said: "When a worker does not get a chance to work and owes mounting accommodation debts to the gangmaster they are in grave danger of exploitation. Debt bondage is a disgrace and I will not stand for it.


"These flowers would be given as Mother's Day and Easter gifts across the UK. I find it unacceptable that loving gifts from a child to their mother could be tarnished by the exploitation of the workers who picked them."


The crackdown also revealed people being charged more than the legal rate for accommodation, having to pay for protective equipment needed to do their jobs and having their passports confiscated by their gangmasters.


Mr Whitehouse added: "The GLA is making its mark in the fight against exploitation. If you suspect worker abuse, including workers in overcrowded housing, or see unfit minibuses used to transport them, tell us and we can do the rest."

Anyone aware of exploitation in the industry should contact the GLA on 0845 6025020.