Frost and fears over so-called swine flu will give the rally in orange juice prices fresh legs, even after a near-doubling in prices over the last year, a leading analysis group has said.

Thanks to this month's cold weather, the decline in orange production in Florida looks set to accelerate beyond the 27.4m boxes that Washington officials have already factored in, the Hightower Report said.

Traders believe that frost may have cost America's biggest citrus-growing state up to a further 10m boxes of oranges, taking the year-on-year fall in output potentially to 23%.

"This should provide support for another leg higher [for prices] into the spring," Hightower analyst Terry Roggensack said.

Flu factor 

Meanwhile, Americans may be rediscovering their taste for orange juice, a factor which, with global economic recovery and potentially a growing foreign consumer base too, may underpin demand.

"The H1N1 virus may have sparked a more permanent shift in consumer demand," Mr Roggensak said.

He added: "Shaving off more production in a period of rising demand should help hold the trend up.

"If we continue to see signs of improving demand for juice in the US and an expanding global economy, the orange juice market is likely to need sharply higher prices just to encourage future growth in production."

Juice for March closed up 0.80 cents at 142.85 cents a pound in New York on Monday, within 8 cents of the two-year high hit two weeks ago.