Rice export prices in top exporter India slid this week to their lowest in nearly seven months as demand continued to stagnate, while rates for Vietnamese rice dipped on the expected increase in stockpiles after the summer harvest.

India's 5 percent broken parboiled variety was quoted around $362-$365 a tonne this week, down from last week's $371-$374 for a sixth weekly decline as it also came under pressure from depreciation in the rupee.

"Demand has dried up in the West African market, as they are sitting on high inventories," said Nitin Gupta, vice president for Olam India's rice business.

Aggressive selling of old inventories by China to African buyers is also weighing on prices, exporters said.

The rice-growing southern peninsula of India could receive 95 percent rainfall during the forthcoming monsoon, private weather forecaster Skymet said.

Meanwhile, neighbouring Bangladesh is planning to export surplus rice to protect farmers' interests, food minister Sadhan Chandra Majumdar said, amid growers' increasing frustration over low rice prices.

Farmers say that 40kg of paddy is being sold at about 500 taka ($5.90) against an average production cost of 700 taka, while the harvesting of the summer rice crop, known as Boro, is in full swing.

In Vietnam, rates for 5 percent broken rice fell to $355 a tonne on Thursday, compared with $365 a week earlier, on expectations that stockpiles will increase when the early harvest of the summer-autumn crop begins late this month.

"Rice exports from Vietnam this year are forecast to stay flat on last year but will gradually fall as the rice growing area is shrinks to give way to growing fruit trees," a senior official with the Vietnam Food Association told Reuters.

"Though Chinese importers have reopened the door to Vietnamese rice, it's not yet easy for Vietnamese exporters to boost their sales to China as several technical barriers are still in place," the official added, referring to regulations on quality management, packaging and origins.

Meanwhile, Thailand's benchmark 5-percent broken rice prices were unchanged at $385-$400 a tonne free on board (FOB) Bangkok.

But Thai traders said they were worried that Thai rice, currently priced higher than Vietnamese and Indian rice, is also losing competitiveness because the Thai baht is the strongest-performing currency in Asia this year.

The Thai Rice Exporters Association stood by its January forecast for Thailand to export 9.5 million tonnes this year, falling from last year's 11 million tonnes because of the strong baht.

Thailand's deputy commerce minister, Chutima Bunyapraphasara, on Wednesday said the country had exported 3.2 million tonnes of rice in the first four months of the year.