About 50 Milton Keynes Council pink recycling sacks were found in a giant area of dumped plastics by a BBC television documentary.
The council said the “most likely” reason they were there was “misuse”.
Council leader Pete Marland said he wanted to ensure all recycling companies were independently audited.
In the documentary, to be broadcast on Monday, Hugh Fearnley-Whittingstall visits the mound of recycling waste found by Greenpeace in the Malaysian jungle.
The authority said all household material collected for recycling was taken to its Materials Recycling Facility in Wolverton, where the sacks were opened and the contents sorted.
The sacks and most other plastic items are processed in the UK and turned into fragments suitable to be manufactured into new plastic goods.
A small amount of plastics are traded to Taiwan for the same process.
“We only work with reputable suppliers who have a clear picture of where recyclable material goes, right throughout the supply chain, and our suppliers have reconfirmed to us that our recyclable materials are dealt with properly,” a spokesman said.
“We do not export waste to Malaysia, and we’re appalled to see this misuse of our recycling sacks. The way much UK plastic waste is treated is shocking and alternatives must be found fast.”
Mr Marland said he had “learned only recently” from council officers that “processed” plastics had been sent to Taiwan, according to the Local Democracy Reporting Service.
“I was under the impression that no recycling materials were taken abroad but that was clarified for me by a statement from our director.”
He said the Environment Agency certified all its supply chains.