Seven people have been arrested for being in possession of 3,800 bales of plastic bags.
Two suspects were arrested in Kapsoit trading centre while five others were arrested in Brooke trading centre as the National Environment Management Authority (Nema) intensified crackdown on the sale and use of plastic bags.
A ban on plastic bags took effect in August 2017.
Nema chief enforcement officer Robert Orina said there was a resurgence of the sale and use of plastic bags in Kericho.
"The plastic bags are being used, especially by small economy traders, because the bags are cheap for use to package, especially groceries," said Mr Orina.
Orina said preliminary investigations indicated that the plastic bags originated from the neighbouring Tanzania and Uganda.
"Kericho is a transit route for the plastic bags from the neighbouring countries brought through the porous Busia border," he said.
The Nema chief enforcement officer vowed that the crackdown would continue until the plastic bags' menace is eliminated.
"We are determined to get rid of the sale and use of plastic paper bags in the county and country in general," said Orina.