The grouping of Mekong nations will be similar to the oil cartel OPEC, and will be called the Organisation of Rice Exporting Countries (OREC).
Prime Minister Samak says Thailand will help the other countries with technical support to improve their production for export.
Thailand is the world's largest rice exporter, and shipped an estimated 9.5 million tonnes of rice overseas last year.
Rice prices have soared this year because of higher fertiliser costs, droughts, the loss of farmland and speculation by commodity traders.
China urges increase in grain reserves
The cost of rise has also been pushed up by export restrictions imposed by several key exporters, including China.
On Wednesday the commerce ministry reaffirmed government curbs on grain exports.
It has urged local governments to increase reserves of grains, meat and cooking oils to ensure supplies and keep food prices in check.
The call, in line with earlier remarks by Premier Wen Jiabao comes at a time when many exporting countries have reduced supplies, pushing world prices of grains, particularly rice, to record highs.
China's grain prices are among the lowest in the world as Beijing constantly releases state reserves to keep prices in check.
However, the rice price in the south has picked up and risen more than 10 percent over the past weeks.