In January inspectors in Jakarta found 89 waste containers exported from the UK as “scrap metal” appeared to contain liquid and other illegal mixed waste.
The Environment Agency said it had begun an investigation and was working closely with Indonesian authorities.
UK companies are not allowed to export contaminated waste to Indonesia.
Certain standards
In 2011, 51 waste containers which were due to be exported were held or returned to the UK, while in 2010 the Environment Agency received 31 requests to repatriate 407 tonnes of waste.
The containers found at the Tanjung Priok port are due to be released at the end of March. They are then expected to take four weeks to reach the UK.
At the time Environment minister Balthasar Kambuaya was quoted as saying that Indonesia accepted scrap metal as long as it met particular standards.
He said: “The material must be safe and clean. These [materials] look like garbage. Some of them are wet, some are dry and some even drip smelly liquids. These clearly violate the law,”