The government has warned consumers against panic buying and businesses against hoarding or price gouging as floods disrupt transport.
Government spokeswoman Ploythalay Laksameesaengjan said agencies had been ordered to ensure supplies of essential goods as flooding, including in Bangkok, was monitored.
Businesses must display accurate prices under the 1999 Prices of Goods and Services Act. Those found hoarding goods, raising prices or exploiting consumers could face up to seven years in prison, a fine of up to 140,000 baht or both.
Ms Ploythalay said the Department of Internal Trade had found supplies were sufficient and there was no justification for price increases. It was coordinating with manufacturers, wholesalers and retailers to check stocks and speed distribution.
Department director-general Wittayakorn Maneenetr said large retailers could replenish stocks as normal, but some convenience stores in flood-hit Bang Kapi, Min Buri and Rangsit faced transport problems.
Most fresh and wholesale markets remained open without shortages, although some had fewer vendors and customers because flooding made travel difficult, he said.
The department was also continuing to monitor production, weather, transport and the operation of shops and markets to assess effects on prices and demand and respond quickly to problems.