ISTANBUL (Reuters) - Food wasted by consumers is an enormous economic problem and nations should ensure excess food is given to the hungry instead of being thrown away, agriculture ministers from the Group of 20 leading countries said on Friday.

The two-day meeting in Istanbul has focused on problems of food security and nutrition, including the impact of climate change. A reduction in the amount of food wasted would improve food security, the ministers said in their final communique.

"We note with great concern the significant extent of food loss and waste ... and their negative consequences for food security, nutrition, use of natural resources and the environment," the ministers said.

"We highlight this as a global problem of enormous economic, environmental and societal significance."

An estimated 1.3 billion tonnes of food, or roughly 30 per cent of global production, is lost or wasted annually, the UN Food and Agriculture Organisation said last year.

UN agencies said this would easily feed the world's 800 million hungry.

To fight the problem, countries need better estimates of the amount of food they waste, as well as the economic impact of food loss, the G-20 ministers said.