Indonesia has asked Britain to take back 1,800 tonnes of waste after inspectors found liquid and illegal mixed waste in containers marked as "scrap metal," Britain's Environment Agency said Friday.

The agency confirmed it had launched an investigation after inspectors at Tanjung Priok port in Jakarta conducted a spot check of the 89 containers in January.

The containers are believed to have included soil and other waste while the Jakarta Globe newspaper reported that customs officials found asphalt, sand, plastics and oozing white liquid.

British companies are forbidden from exporting contaminated waste to Indonesia.

The containers are expected back in Britain later this month.

Indonesian Environment Minister Balthasar Kambuaya stressed in January that his country only accepted scrap metal if it met certain standards.

"The material must be safe and clean," he said. "These (materials) look like garbage. Some of them are wet, some are dry and some even drip smelly liquids. These clearly violate the law."

Andy Higham, who is leading the Environment Agency probe, vowed "vigorous action where there is evidence of waste being exported illegally."