Stockholm - Three agencies including the UN Food and Agricultural Organization (FAO) said on Thursday that reducing food waste was a means to improve global water conservation and shore up future food production.

The call was made during World Water Week, currently taking place in Stockholm, where scores of experts and policy makers have gathered to discuss water and sanitation related issues.

A British researcher was to receive the 150,000-dollar Stockholm Water Prize, administered by the Stockholm International Water Institute (SIWI), on Thursday for launching the concept of "virtual water" - a system that measures the amount of water used to produce and trade goods.

Professor John Anthony Allan, of King's College London and the School of Oriental and African Studies, pioneered the concept of virtual water in the early 1990s.

The Water Prize jury said Allan had made "unique, pioneering and long lasting work in education and raising the awareness internationally of the interdisciplinary relationships between agricultural production, water use, economies and political processes."

Examples of "virtual water" would be the estimates that 140 litres of water are needed to grow, produce, package and transport a cup of coffee, a hamburger needs 2,400 litres of water, while a pair of jeans uses some 10,000 litres.

Each US citizen consumes about 6,800 litres of virtual water per day, counting all the water embedded in the production of goods like food and clothes. That is about three times the average for each Chinese national, the Stockholm International Water Institute said.

SIWI, along with the UN food agency FAO and the International Water Management Institute (IWMI) compared discarded food to leaving the tap running in a joint report "Saving Water: From Field to Fork - Curbing Losses and Wastage in the Food Chain".

"As much as half of the water used to grow food globally may be lost or wasted," IWMI researcher Charlotte de Fraiture said.

Some 1.2 billion people were estimated to live in regions where demand for water is greater than supply. The pressure is increasing over demand for agricultural products like beef and bioenergy that are water intensive.

Most uneaten food is lost before it is consumed in poorer countries, with 15 to 35 per cent lost in the field and a further 10- 15 per cent discarded during processing, transport and storage, the joint report said, noting that waste of food was greater in richer countries.

In the US it was estimated that each year up to 30 per cent of food, worth some 48.3 billion dollars is thrown away.

The report called for improving awareness and better environmental education to reduce food waste by targeting schools, hospitals and offices. (dpa)