There is also a big question mark over Iran and Indonesia, two countries that normally buy as much as 1 million tonnes of Thai rice each year but which have bought nothing so far in 2008 because of the soaring prices.
Even though some analysts say the price, part of a wider global rally in crop prices, is based on jittery governments rather than fundamentals, Thailand's top exporters say the world is now set for an era of expensive food.
"Prices will remain firm for the rest of the year," said Chookiat Ophaswongse, head of the Rice Exporters Association in Bangkok.
Rice futures on the Chicago Board of Trade climbed 2.5 percent on Wednesday to an all-time high of $24.85 per hundredweight.
However, grain futures tumbled four percent to a five-month low due to expectations of a large global wheat crop in 2008.
With the northern hemisphere harvest only two months away, officials said planting had started well in Western Australia after good rains, while India said a record harvest and bulging government stocks meant no imports were needed this year.
China's top wheat-growing provinces of Henan and Shandong were also looking at a bumper winter harvest after recent rains, the Xinhua news agency said.
CRTICISM OF EXPORT CURBS
Brazil became the latest country on Wednesday to suspend rice exports, following in the footsteps of India and its close rival for the mantle of world number-two supplier, Vietnam.
Thailand, which accounts for nearly a third of all rice traded globally, has said repeatedly it would not impose any curbs, a stance that has earned it plaudits from the World Bank for being a "responsible international trading partner."
"Thailand has even gone the extra mile to explore additional land for rice production," James Adams, the bank's Vice President for East Asia Pacific, said in a statement.
The Asian Development Bank and free-trade advocates have criticized the export curbs as an overreaction that has distorted the market.
"If we restrict trade, we're simply going to add food scarcity to the already large problems of food shortages that exist in different countries," EU Trade Commissioner Peter Mandelson said.