Almost 2,000 tonnes of contaminated waste will be shipped back to Britain after being seized in Indonesia, investigators said today.
Authorities believe 90 containers exported from the UK as "scrap metal" were illegally packed with liquid and mixed waste.
The Environment Agency said it was liaising with Indonesian authorities as part of efforts to find the gang behind the export.
The agency said Indonesian authorities have requested repatriation of the containers, which could take a month to send back.
Under international law, Indonesia may accept scrap metal for recycling - but contaminated waste cannot be exported.
The containers are due to be released for repatriation at the end of this month.
Andy Higham, who is leading investigations for the agency, said: "We are working closely with the Indonesian authorities to establish the facts of this case.
"Illegal waste exports risk harm to human health and the environment in the country of export, it also undermines law-abiding recycling businesses back home.
"There is a legitimate export market for recyclable material. However, we will take vigorous action where there is evidence of waste being exported illegally."
The Environment Agency will oversee the arrival of the containers before undertaking an inspection of their contents.