Prices for rice, a food staple in much of Asia, have tripled over the past year and the World Bank warns that higher rice prices could push millions deeper into poverty. But a leading rice authority says there is no shortage of rice and that export bans have aggravated a spike in prices. VOA's Barry Wood reports.

Nathan Childs is a rice specialist at the US Department of Agriculture. He says that, while higher fuel and fertilizer costs caused a steady rise in prices over the past two years, there is another explanation for the rapid run in prices over the past four months.

"The primary reasons for the recent price spike in rice are due to export bans on restrictions by several major exporters globally that have tightened supplies in the global market. Overall though, the 2007-2008 rice crop is the largest on record and supplies are up a little bit from a year earlier," he said.

The major rice exporters -- Thailand, Vietnam, India and China -- have restricted exports to sell more product domestically to drive down local prices. That strategy, says Childs, has triggered unjustified fears in importing nations that rice is in short supply. Childs says there is no shortage of rice on the world market.

In addition to the export restrictions, Childs says, higher fertilizer and shipping costs and the weak US dollar have also contributed to the price rise.

"Because most rice in global markets is traded in dollars. So when the dollar declines, as a foreign currency is converted to dollars, it raises its dollar value. So some of the increase in global rice prices is due to the fact it was traded in dollars," he said.

The dollar has declined by up to 20 percent against major currencies in the past two years.

Childs and other rice analysts say they do not expect prices to remain at their current high levels. However, they do not expect the prices to come down to the levels of two years ago.