April 24 (Bloomberg) -- Rice advanced above $25 for the first time as Wal-Mart Stores Inc.'s Sam's Club warehouse unit restricted purchases of some types of rice in the U.S.

The cereal, the staple food for half the world, has more than doubled in the past year as China, Vietnam and India curbed exports to safeguard domestic supplies. Sam's Club limited customers to four bags of jasmine, basmati and long-grain white rice per visit in all U.S. stores where allowed by law, company spokeswoman Kristy Reed said by e-mail.

Consumers have started hoarding rice as supplies shrink. Thailand, which ships one third of the world's exports, may restrict sales, a World Bank official said this week. Wheat, corn and soybeans gained to records this year, spurring social unrest in countries including Haiti and Egypt.

``We have been neglecting our basic rice production infrastructure and research and development for 15 years,'' said Robert Zeigler, director-general of the International Rice Research Institute in the Philippines. ``National hoarding really doesn't help the market,'' he told Bloomberg Television.

Rice rose as much as 0.9 percent to $25.01 per 100 pounds in Chicago today and has climbed 26 percent this month, heading for its biggest monthly gain since October 1993.

The U.S. warehouse clubs are trying to protect business customers, like smaller restaurants, caterers, nursing homes and day-care centers, said Jim Degen, principal of J.M. Degen & Co., a food industry advisory firm based in Templeton, California.

UN Secretary-General Ban Ki-Moon said April 20 rising food costs may hurt economic growth and threaten political security. The World Bank has forecast that 33 nations from Mexico to Yemen may face social unrest because of higher food and energy costs.

Brazil Curbs

Brazil may curb exports of rice to build domestic inventories, Agriculture Minister Reinhold Stephanes said in Brasilia yesterday. The government is seeking an agreement with producers to ensure the country has enough rice.

Japan, the world's biggest net food importer, will ask the World Trade Organization as early as next week to introduce rules to stop countries restricting grain exports, Hiroaki Kojima, deputy director for international economic affairs at Japan's Agriculture Ministry, said on April 22.

Persuading the WTO to intervene may be tough for Japan, which protects its agriculture with subsidies and import tariffs as high as 700 percent on farm products. Developing nations are pressing Japan to cut the duties and open its market in the Doha Round of trade talks.

Import Delay

Japan, which is self-sufficient in rice, will delay seeking imports of the grain required under a WTO agreement until international prices stabilize, a government official said in an interview in Tokyo. The country imported 630,550 tons of rice in the year ended March 31, part of a WTO agreement to seek 770,000 tons.

Thailand may follow its Asian neighbors in limiting sales, said James Adams, vice president of the bank's East Asia and Pacific department April 21. The country's Prime Minister Samak Sundaravej said April 22 his country won't impose curbs on overseas exports or distort prices.

Malaysia's government said it will discuss rice imports from Thailand at a meeting today with Samak outside Kuala Lumpur. The talks are a ``top priority,'' Malaysian Foreign Minister Rais Yatim told reporters today.

Still, there are signs that record prices are encouraging farmers in Asia to increase production.

The Philippines, the world's biggest rice importer, may reduce the volume it's seeking to buy at a tender next month, after production exceeded target, Agriculture Secretary Arthur Yap said by phone today.

The country planned to buy 500,000 metric tons of rice May 5. The Southeast Asian nation has already produced 6.9 million tons of rough rice so far this year, Yap said. That's 200,000 tons more than the target for the first half.

To contact the reporters for this story: Feiwen Rong in Singapore at frong2@bloomberg.net; Cotten Timberlake in Washington at ctimberlake@bloomberg.net

Last Updated: April 24, 2008 01:44 EDT