Cambodia is investigating a locally based Chinese firm for illegally importing around 1,600 tonnes of plastic waste from the United States and Canada, the Southeast Asian country's customs chief said on Friday. Southeast Asian nations have emerged as some of the top destinations for plastic waste exporters in the West after China introduced a partial ban on waste imports in 2018 which disrupted the flow of more than 7 million tonnes of plastic scrap a year. Kun Nhim, director general of Cambodia's General Department of Customs and Excise, told Reuters that a Chinese firm based in Cambodia had imported the waste, which was discovered this week in 83 shipping containers at the Sihanoukville Autonomous Port. "There will obviously be fines, although how much will depend on our law, and the company may face termination if it is found to have committed a crime," Mr Nhim told Reuters. He identified the company as "Chingyuen", but Reuters was unable to trace a company of that name. On Wednesday, Cambodian authorities said that they would send the waste back to its stated countries of origin - the United States and Canada. The US Embassy in Phnom Penh said it was aware of the reports. "We have requested additional information and are offering US government assistance to determine both the exporter (country of origin) and the importing entity here in Cambodia," Embassy spokeswoman Emily Zeeberg told Reuters. The Embassy of Canada in Phnom Penh did not immediately respond to request from Reuters for comment. The containers had been arriving over a period since October 2018, Mr Nhim said. They had been mislabelled as "recycled products", according to Neth Pheaktra, Secretary of State at Cambodia's Ministry of Environment. "The Royal Government of Cambodia does not allow the import of plastic waste to be recycled in Cambodia," Mr Pheaktra said. "Cambodia is not a waste bin". A ship carrying 69 containers of waste mislabelled as plastic returned to Canada last month from the Philippines, closing a chapter on a dispute that started in 2013 and sparked a diplomatic furore between Ottawa and Manila.