The government acknowledged for the first time rice exports in 2013 will reach a mere 6.68 million tonnes worth US$4.38 billion, down by 3.9% and 7.9%, respectively.
The amount is far below the forecast range of 8 million to 8.5 million tonnes for the year.
Surasak Riangkrul, director-general of the Foreign Trade Department, blamed the drop on higher prices for Thai rice than for Indian and Vietnamese grains and a delay in purchases by several rice-importing countries such as Indonesia.
Mr Surasak said 60% of the rice shipments stemmed from government sales of rice stocks, but Chookiat Ophaswongse, honorary president of the Thai Rice Exporters Association, said Mr Surasak's claim is impossible.
"If the government's rice stock sales made up 60% of the country's overall rice shipments, this is tantamount to the government selling as much as 3-4 million tonnes and the private exporters selling only 2 million tonnes," said Mr Chookiat.
"This is impossible. Parboiled rice, which is sold only by exporters, is equal to 2 million tonnes this year. That would mean the exporters sold hardly any white rice."
He said the figures claimed by the department are most likely inaccurate.
"The National Anti-Corruption Commission is expected to rule soon over the scope of government-to-government (G2G) rice sales," said Mr Surasak.
"G2G deals should be made with a letter of credit concerning the deal issued to the Foreign Trade Department, not how it's done now with the government assigning certain rice exporters to sell state rice stocks on its behalf."
In November, Mr Surasak said the government had sold 7-8 million tonnes of its rice stockpile over the last two years through G2G contracts.
The government remains adamant its remaining stockpile is 10 million tonnes, though industry sources put the amount closer to 16-17 million.
He predicted rice exports in 2014 of 8 million tonnes worth $4.8 billion. Once again, rice sold through G2G deals will account for 60% of the country's total rice shipments, he said.
The department expects to fetch 130-140 billion baht from selling rice stocks via G2G contracts in 2014, and to pay back the Bank for Agriculture and Agricultural Cooperatives (BAAC). The Commerce Ministry repaid 140 billion baht to the BAAC in 2013, he said.