HANOI -- Vietnam's trade minister on Friday called on the country's rice exporters to honour their export contracts to maintain demand despite a recent surge in prices for the staple grain, state media reported. "It's unacceptable for a rice exporting country to face tight supplies and high domestic prices," Dien told the conference. Vietnam's rice paddy output is expected to rise to 43 million tons this year from 42.7 million tons last year, the head of the country's Department of Crop Production said on Tuesday. Rice shipments from Vietnam, the world's third-largest exporter after India and Thailand, are expected to reach 7.8 million metric tons this year, up from 7.1 million tons recorded last year. Exports in the first seven months of this year were estimated to have risen about 18.7% from a year earlier to 4.84 million metric tons, according to preliminary government data.