Many traders now use increasing transportation fees to force farmers in the Cuu Long (Mekong) River Delta to reduce produce prices, resulting in uncertainty about profits for farmers.

“Traders say the increase in costs is due to the monitoring of weights of transportation vehicles, now being checked nationwide, and rising petroleum prices, making deliveries more costly," Vo Van Ut in Tien Giang province said.

"Our rice prices have to be decreased so they can compensate for the charges, so we farmers have to bear greater expenses from production to distribution," he added.

Vietnam Food Association vice chairman Pham Van Bay said the nation's farmers were facing significant damages, especially when fertiliser and seed costs were unfavourable for them.

Since April, in Tien Giang, Long An and Ben Tre provinces, the prices of mangos and dragon fruits fell by 5,000-10,000 VND (0.24-0.48 USD) per kg. Also, many types of vegetable, including cabbage, tomato and pumpkin buds could not be sold and had to be used to feed cattle and poultry.

Meanwhile, agricultural produce prices remain high and even increased in both traditional markets and supermarkets.

In the Binh Dien and Tam Binh key markets, vegetable prices are 2,000-5,000 VND (0.10-0.24 USD) higher than two to three weeks ago. Fish and shrimp prices also have seen 5,000-10,000 VND (0.24-0.48 USD) hikes.

Small traders here also attribute the price increases to more expensive transportation and fuel charges.

Most transportation companies say they usually make profits by allowing vehicles to carry goods with weights exceeding the levels allowed by the law. But now, as vehicles are being strictly checked by authorities, many of them have suffered losses.

Officials from a firm said that with a 15-tonne truck carrying the permitted weight, it would be difficult for it to hire a driver and cover fuel costs if it maintained a transportation charge of 130,000-140,000 VND (6.19-6.67 USD) per tonne.

"In my opinion, the tight supervision of vehicle weights will create equality for transportation enterprises. The price of goods will rise in the short term, but they will become stable in the long run," said Tran Quoc Dung, the owner of a transportation firm in Ho Chi Minh City.-VNA