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Speakers at a United Nations forum on Monday urged the world's poorest nations to help their vulnerable citizens by pursuing good governance, while some leaders said rich countries had not done enough to help developing regions.

U.N. Secretary-General Ban Ki-moon was among some 8,000 delegates who converged on Istanbul for the conference on "least-developed countries," which lists 48 members in its ranks. Thirty-three are in Africa, 14 are in Asia and one — Haiti — is in the Americas.

The five-day conference opened with dire warnings about the threat of rising food and fuel prices, and climate change, to the poor, but there were also calls to seize investment opportunities in developing countries.

Turkey's role as host allowed it to highlight its growing economic and diplomatic clout, though Prime Minister Recep Tayyip Erdogan took the opportunity to warn that "the rage to consume, the growing gap between rich and poor" would foment global insecurity.

"We observe with great sadness that developed, rich countries have not shown sufficient interest in this important summit," said Erdogan, whose government has sought to balance its traditional Western alliances with stronger ties in the Middle East and elsewhere.

Turkey's warm relationship with Iran has troubled Western governments who suspect the Islamic Republic of seeking to develop nuclear weapons, though Tehran says its program is peaceful. Iranian President Mahmoud Ahmadinejad, whose oil-rich country is not in the U.N. list of poorest countries, traveled to Istanbul for the conference.

In a speech, Ahmadinejad said "weaknesses and shortcomings" of some developing nations could be attributed to the legacy of colonial powers that he said exploited natural resources and engaged in devastating wars in a bid to retain control. Even today, he said, the "same global powers" were seeking to "plunder" the wealth of vulnerable nations.

He proposed that 10 percent of the military budget of powerful countries be allocated to the poorest nations, and that Iran was ready to join such a development effort.

"They should not be treated like homeless people," Ahmadinejad said.

According to conference organizers, the group of least-developed countries accounts for nearly 13 percent of the global population, but just 1 percent of world trade. They noted, however, that some of those countries, known as LDCs, have enjoyed relatively high growth rates in recent years.

"Investing in LDCs is not charity. It's an opportunity for all," said Ban, the U.N. chief. "Investing in LDCs can provide the stimulus that can help to propel and sustain global economic recovery."

The last such conference was hosted by the European Union in Brussels in 2001, and Ban said it was vital to ensure the long-term monitoring of any promises of assistance from developed and emerging economies.

"We have received a lot of very generous pledges in the past, but not all of them have been delivered," he said.

Ngozi Okonjo-Iweala, managing director of the World Bank, said that in order to complement help from the international community, poor countries must "look within" to create favorable conditions for growth. She said accountable institutions and citizen involvement in decision-making would help contain conflict and manage crises, including natural disasters.

Former World Bank President James D. Wolfensohn said governance in poor countries was critical to the good use of funds aimed at reducing poverty, and that "civil society" groups were often full of goodwill but failed to coordinate.

He said that during his 10 years at the helm of the World Bank, he usually anticipated that corruption would reduce the efficiency of bank projects by between five and 30 percent. Graft, Wolfensohn said, was still a taboo topic.

"It exists and it gnaws at the effectiveness of what we do," he said in a speech. "It has not been mentioned this morning for reasons that I don't understand."

Turkey is paying for up to 11 delegates from each of the 48 poor nations to travel to Istanbul for the conference, which has also attracted aid organizations, parliamentarians, academics and business executives.

The group of poor nations includes Afghanistan, where a U.S-led coalition is fighting Taliban insurgents, and Yemen, where the government has cracked down on protests aimed at ousting the president.

Since the United Nations introduced the category of least-developed countries decades ago, only Botswana, Cape Verde and Maldives have developed enough to be removed from the list.

Qualification includes a per-capita annual income of less than $905, and assessments of malnutrition, child mortality and education levels, as well as an "economic vulnerability" rating based on population size, remoteness and instability in exports and production.