ROME (Reuters) - Government leaders and officials meet in Rome on Monday for a three-day U.N. summit on how to fight global hunger, but anti-poverty campaigners are already writing off the event as a missed opportunity.

With the world's hungry topping one billion for the first time in history, the U.N. Food and Agriculture Organisation had called the summit, hoping that leaders would commit to raising the share of official aid spent on agriculture to 17 percent of the total -- its 1980 level -- from 5 percent now.

That would amount to $44 billion a year, up from $7.9 billion now.

But a published draft of the final declaration to be adopted on Monday includes only a general promise to pour more money into agricultural aid, with no target nor a timeframe for action.

A pledge to eliminate malnutrition by 2025 was also taken off the draft, which now states that world leaders commit to eradicate hunger "at the earliest possible date".

"The real causes of hunger and food insecurity are not even on the agenda or in the draft declaration," said the London-based think tank International Policy Network, which blames trade restrictions for the rise in malnutrition.

Last year's spike in the price of food staples such as rice and wheat sparked riots in 60 countries, hoarding and a scramble by rich food importers to buy foreign farmland, pushing food shortages and hunger up the political agenda.

Food prices have fallen back since, but they remain high in poor countries and FAO warns sudden price rises are very likely.