CUSTOMS & Excise is preparing to step up enforcement of the aggregates levy to ward off rogue firms.
Department officials told the Quarry Products Association Northern Ireland that they would 'see evidence of active enforcement on the ground in the next four to six weeks'.
Customs has already visited 50 construction firms and is planning to intensify the campaign over the next two months.
QPANI regional manager Gordon Best said: 'We welcome further enforcement of the levy.
'But we also asked them to tell the Treasury that this tax is flawed. We believe that a code of environmental practice would look after the future of the quarrying industry in the province.'