The ban in place since early this month would help "ensure food security and meet best with the state's interest", Deputy Industry and Trade Minister Nguyen Thanh Bien was quoted as saying.

It would also help reduce the volume of rice on the export market, pushing up prices and raising export earnings over time, he said.

Early this month the government extended the ban to help stabilize domestic food prices as it tries to tame double-digit inflation. Prior to that, it had curtailed exports for March and April, while allowing shipments under deals signed earlier.

Vietnam's southern region, incorporating the Mekong Delta food basket, is expected to harvest 9.9 million tons of export-quality, winter-spring paddy this year, up 3.9 percent from last year.

The official Vietnam News Agency-run Tin Tuc newspaper quoted Bien as saying global prices would continue to rise until 2010.

"Vietnam has made a record with its rice offer price to the Philippines reaching $1,200 a ton and rice prices are expected to rise to $1,500 per ton next month," he was quoted as saying.

The Philippines, where the authorities are nervous about people taking to the streets if rice shortages develop, has raised the amount of rice it wants to buy at its May 5 tender by 35 percent to 675,000 tons after failing to buy enough at previous auctions.

The International Grains Council has said prices at the tender could hit $1,500 to $1,600 a ton, after Manila paid an average price of $1,135.8 to $1,139.11 per ton, cost and freight, for the 25 percent broken rice and 5 percent broken varieties at an April 17 tender.

Vietnam, which has been the Philippines' main source of rice, estimated on Friday its earnings from the export of 1.57 million tons of rice in the first four months of 2008 would soar 72.7 percent from last year to $775 million due to high world prices.

However, inside Vietnam, rice prices have risen 25 percent this month from the end of March and surged 85 percent since last April to 5,500 dong (35 U.S. cents) per kg of paddy as of Friday.

Vietnam estimated on Friday that annual inflation in April jumped to 21.42 percent, among the highest in Asia.

Food prices, which account for 42.8 percent of the basket Vietnam uses to calculate inflation, were 38.21 percent higher this month than at the same time last year, the government said.

Source: Reuters