Pol Maj-General Thirapong Wongratphithak, commander of Metropolitan Police Division 4, on Monday said Arthit Boonyaprateep, 38, had been arrested at a checkpoint on the Pradit Manootham road in front of the CDC shopping mall.
Police found 400,000 meth pills and 5kg of crystal meth in his car.
He was taken to his rented room on Soi Mahatthai, where police found a further 253,000 meth pills.
His confession then led police to seize another 6 million meth pills and 444kg of ice from a pickup truck at his house in Ayutthaya’s Wang Noi district, Thirapong said.
Police are conducting an investigation with a view to apprehending Arthit’s accomplices, the commander added.