HANOI, July 12 (Reuters) – Vietnam has set a floor on rice export prices at $300 a tonne to stem further falls in domestic prices during the peak of a major harvest, state-run newspapers said on Monday.

Truong Thanh Phong, chairman of the Vietnam Food Association, made the request last Friday, before businesses started buying on Saturday 1 million tonnes of summer-autumn rice for stockpiles, the  Vietnam Agriculture newspaper, run by the country's farm ministry, said.

The report did not say what rice grades the new floor price applies to, but is a significant cut from $350 a tonne, free on board, set in April for 25 percent broken rice .

Last week Vietnamese 5 percent broken rice fell to $340-$350 a tonne from $350-$360 the previous week, and the 25 percent broken grain eased to $305-$310 a tonne from $305-$320.

Last Friday the food association met rice export firms, provincial authorities in the Mekong Delta and officials from the trade and finance ministries to review rice exports in the first half and the export outlook for the last six months as well as the government-backed stockpiling plan.