World leaders on Thursday concluded a three-day summit on global food security, but the high-profile efforts to eradicate hunger were attacked by critics as lacking luster.

"A single meeting cannot solve world hunger but we certainly expected far more than this," said Gawain Kripke, spokesperson for international aid agency Oxfam.

"The result is not commensurate with the problem which is historically huge -- a billion people now facing hunger and looming climate change," he said. "The near total absence of rich country leaders sent a poor message from the beginning."

Worldwide, 1.02 billion people are suffering from hunger and malnutrition this year, more than at any other time, and a child dies of malnutrition every six seconds.

"This is an unacceptable blight on the lives, livelihoods and dignity of one-sixth of the world's population," the leaders said in a declaration adopted on the first day of the summit, hosted by the UN Food and Agriculture Organization (FAO).

But world leaders fell short of making concrete commitments. Even FAO director-general Jacques Diouf said he felt upset that world leaders merely "committed to general goals but without setting precise dates for the total eradication of hunger in the world nor figures regarding the funds necessary to increasing agriculture investments in order to double food production by 2025."

The FAO said underinvestment in agriculture in the developing world has been a root cause of the global food insecurity. It has sought a pledge from rich countries to provide 44 billion U.S. dollars per year to help poor countries.

It also wanted rich countries to commit to a timetable of eradicating hunger by 2025.

"World leaders agreed on the urgency of eradicating world famine, but they have not said when," Diouf said. "The target year of 2025, though previously set-forth by other countries in previous summits, unfortunately was not globally endorsed today."

The declaration made no mention of the target of eradicating hunger by 2025 and any new financial commitments. It only said world governments will reinforce all their efforts to meet by 2015 the targets of reducing hunger by half and take action towards sustainably eradicating hunger "at the earliest possible date."

"We heard the platitudes but nothing new was offered to reverse the decline of agricultural support," Kripke said. "Investing in agriculture is a critical mechanism to reduce hunger and poverty."

The reluctance of rich countries to make concrete commitments was matched by the absence of their leaders at the summit.

The majority attendees to summit came from African, Latin American and Asian countries, among them Brazilian President Luiz Inacio Lula da Silva, Zimbabwean President Robert Mugabe and Libyan leader Muammar Gaddafi.

By contrast, only a handful of rich countries had sent their heads of state or government to the summit. Apart from Italian Prime Minister Silvio Berlusconi, all leaders of the Group of Eight (G8) rich countries skipped it.

"Sixty leaders are coming from around the world to this important UN summit, but where are the leaders from all the G8 countries?" asked international anti-poverty agency ActionAid. "This does not signal they are serious about finding global solutions to hunger."

Despite a lack of real progress, world leaders set out a five-point action plan to ensure sustainable global food security.

They agreed that both national investment and international support should be intensified, global food security governance should be improved, the functioning of food markets should be enhanced, and multilateral institutions need reform.

Ahead of the summit, both Diouf and UN Secretary-General Ban Ki-moon went on a 24-hour fast to show solidarity with people who suffer from hunger.

Opening the summit, Ban called for a global deal on climate change to ensure food security, urging world leaders to take concrete measures to eradicate world famine and forge a deal at the Copenhagen meeting next month on global warming.

There "can be no food security without climate security," he said.