A U.N. summit pledged to cut trade barriers and help poor farmers on Thursday to fight hunger threatening 1 billion people, but poverty campaigners said this was not enough to cap high world food prices.

The three-day Rome summit of 183 countries narrowly avoided embarrassing failure when Latin Americans protested at criticism of export curbs in the final declaration, which committed to "eliminating hunger and to securing food for all, today and tomorrow".

The U.N. Food and Agriculture Organisation called the summit to discuss the impact of poor harvests, high fuel costs and rising demand, especially from fast-growing Asian countries, and there was a row over biofuels.

"We firmly resolve to use all means to alleviate the suffering caused by the current crisis, to stimulate food production and to increase investment in agriculture, to address obstacles to food access and to use the planet's resources...," the declaration said.

The Rome debate on the potential benefit to poor farmers of new global trade rules will feed into a push to conclude the Doha round of World Trade Organisation talks.

But trade was a sticking point, with food exporter Argentina objecting to criticism in the declaration of export curbs like those it has imposed to shield consumers from food inflation.

U.S. Agriculture Secretary Ed Schafer said countries should understand that such restrictions cause food price inflation. Asian rice stockpiling is blamed for high rice prices that have even led to riots.

"We understand that countries want to protect their food supply and make sure that there's enough food for their own citizens but when there's a lock-out from the marketplace ... prices actually go up," Shafer told reporters in Rome.

Delegates said Rome had succeeded at the very least in putting soaring food prices at the top of the global agenda.

Schafer said it had rallied support for "expanded food production ... trade liberalisation and recognises the important role of investments in science and technology in ensuring food security in the long term".

BIOFUELS FEATURED

Cuba and allies Venezuela and Argentina objected to the declaration which Cuban delegate Orlando Requeijo Gual said "neglects the vital needs of those who suffer from hunger".

He hit out at the "sinister strategies of using grain for fuel", a reference to biofuels, which critics say divert crops from food to cars.

The United States and Brazil defended using maize and sugar cane respectively to make ethanol to fuel cars, saying it is a minor factor in food price inflation. The declaration referred to both the "challenges and opportunities" of biofuels.

An international producers' group welcomed this, calling biofuels a sustainable solution to food and energy security.

Commodity prices have doubled over the last couple of years and the World Bank says 100 million people risk joining the 850 million already going hungry.

The Organisation for Economic Cooperation and Development sees prices of rice, corn and wheat retreating from peaks but still up to 50 percent higher in the next decade and the FAO says food output must double by 2050 to meet demand.

The Rome summit was not meant as a fund-raiser but followed large food aid pledges including $1.5 billion from the Islamic Development Bank, $1.2 billion in World Bank grants and loans and $500 million from Saudi Arabia to the World Food Programme.

Oxfam's Barbara Stocking said these donations meant it was "a mistake to dismiss this summit as a waste of time" but added that the Group of Eight rich nations face "a credibility crunch" at July's Japan summit and must show this is all new money.

"Good ideas in Rome need to be followed by cheques in Japan," she said.