Malaysia will return 450 tonnes of contaminated plastic waste to the countries that shipped it, in a refusal to become a dumping ground for the world's trash.

Nine shipping containers at Port Klang, west of Kuala Lumpur, on Tuesday were found to contain mislabeled plastic and non-recyclable waste, including a mixture of household and e-waste.

Yeo Bee Yin, minister of energy, science, technology, environment and climate change, said the plastic was shipped from the US, the UK, Australia, Japan, China, Saudi Arabia, Bangladesh, the Netherlands and Singapore.

Five containers of waste were returned to Spain last month.

On April 24, Malaysia launched a joint task force to crack down on the growing problem of illegal plastic waste imports. The authorities have since carried out ten operations.

Last year, China banned plastic waste imports as part of an initiative to clean up its environment. That move caused a ripple effect through global supply chains, as middlemen sought new destinations for their trash, including Malaysia.

A recent Greenpeace report found that during the first seven months of 2018, plastic waste exported from the US to Malaysia more than doubled compared to the previous year.

Yeo told a press conference that one UK recycling company had exported more than 50,000 metric tonnes of plastic waste in about 1,000 containers over the past two years.

“We urge the developed countries to review their management of plastic waste and stop shipping garbage to developing countries,” Yeo added.

The row over plastic waste imports is also playing out in the Philippines, where Canada recently missed a May 15 deadline to take back tonnes of its garbage.

That prompted a diplomatic spat with Philippine President Rodrigo Duterte, which saw him recall his ambassador to Ottawa.

After Duterte said he was prepared to “declare war” on Canada over the issue, the Canadian government said it would cover the full cost of the return operation and pledged that the garbage would be brought back before the end of June.

Last year the governments of 187 countries, including Malaysia, agreed to add plastic to the Basel Convention, a treaty that regulates the movement of hazardous materials from one country to another, to combat the dangerous effects of plastic pollution worldwide.