Waste management firm Materials Recovery has been found guilty of illegally exporting waste plastic to India.
Magistrates last week ordered the company to pay £25,800 in fines and costs after it regularly broke international shipping rules over a five-month period.
During this time the Environment Agency (EA) kept Materials Recovery under surveillance, culminating in the inspection of a shipping container seized by HM Customs at Southampton docks on November 3 2003.
EA environment officer Andy King said: "Materials Recovery breached UK, European and international legislation."
"All exports of plastic waste except PET can only be exported in line with Red List controls. This basically means these non-PET exports were illegal."
The export of recyclable materials uses a traffic-light coding system.
Materials like used cardboard can be sent abroad for recycling under a green list code.
Mixed material or material that needs special care is coded amber and material that cannot be sent is coded red.
"We don't know what was happening to this plastic once it reached India but the export of waste for disposal is strictly prohibited outside the UK," added King.
"This is to prevent us dumping our waste on developing nations."