The suspect was named as Phuwa Sripanya, aged 29. He is the son of former Bhumjaithai Party MP Panya Sripanya.
Pol Sen Sgt Maj Somporn Thanasisangkul was on a patrol in Khon Kaen's Muang district when he spotted Mr Phuwa acting suspiciously in his car. When the officer approached Mr Phuwa, he refused to talk and drove away to a gas station nearby.
The officer followed him, searched his car and found 600 speed pills and one gramme of crystal methamphetamine with an estimated street value of about 200,000 baht.
Mr Phuwa allegedly confessed that he received the drugs from a drug courier and planned to deliver them to a client who was waiting near an ATM booth in front of the provincial adminitrative court on Thursday night.