The National Environment Management Authority (Nema) has impounded 1.7 tonnes of plastic bags in Mombasa which were being ferried from Tanzania.
According to Nema Mombasa boss Stephen Wambua, the importer of the 8.5 million pieces of the banned plastic bags is still at large.
"But police have launched manhunt for the suspect. He imported the banned consignment into the country," Mr Wmbua said.
He said he received a tip off Sunday morning that plastic were bags transported from a neighbouring country to Mombasa and he laid an ambush with the help of the police.
"We impounded 17 bales of plastic bags which were found to have been offloaded from a Simba Coach bus registration number KBU 343C at the Simba Coach Offices at Mwembe tayari. Each bale is estimated to contain over 500,000 pieces," Mr Wambua said.
Speaking to the Nation, the Nema boss said the owner of the consignment who was identified as Mr Issa escaped.
"The 17 bales are at the Central Police Station and efforts are being made to arrest the importer of the banned plastic bags," he said.
He warned traders against importing the banned polythene bags, saying they will face stiffer penalties.
Mr Wambua urged residents to always use eco-friendly bags.
He also cautioned transporters against being used as conduits to ferry contraband goods into the country.
This comes as small scale traders continue to defy the government ban on the use of plastic bags.
Most markets at the Coast including Kongowea, the largest in the region, still use plastic bags to wrap items for their customers.