The consumer price index rose 4.03 percent in the month from a year earlier, against a gain of 4.29 percent in August, the commerce ministry reported.

"Many factors such as the government's fuel policy and a stronger Thai baht ... helped reduce inflationary pressure," said Commerce Ministry official Yanyong Phuangrach.

Thailand's new government has suspended a levy on petrol and diesel, leading to a drop in prices. On the other hand, food prices continue to rise.

The Thai central bank raised its key interest rate in August for the sixth time this year, to 3.50 percent -- the highest level in about three years -- saying inflation was a bigger threat than a slowing global economy.