Cuban President Raúl Castro called on Latin American and Caribbean leaders Tuesday to work together on pressing regional problems at a gathering of all Western Hemisphere nations except the U.S. and Canada.

In his keynote speech as host for the summit of the Community of Latin American and Caribbean States, or CELAC for its initials in Spanish, Castro argued that the bloc should aspire to unity despite diversity, describing it as "the legitimate representative of the interests of Latin America and the Caribbean."

"We should establish a new regional and international cooperation paradigm," Castro said. "In the context of CELAC, we have the possibility to create a model of our own making, adapted to our realities, based on the principles of mutual benefit."

The summit's main theme is fighting poverty, inequality and hunger. According to the UN's Economic Commission for Latin America and the Caribbean, 28 percent of the region's inhabitants live in poverty and 11 percent in extreme poverty.

But if unity and feel-good talk about lifting up the poor were the order of the day, Castro also heard a rebuke from U.N. Secretary-General Ban Ki-Moon, who was invited as an observer and met with the Cuban leader Monday.

During his first trip to Cuba, Ban praised Havana for its historical preservation efforts, its international medical missions that treat the poor and its work fighting violence against women and girls. But he also criticized the Communist-run nation on human rights.

"I emphasized the importance of playing a greater role in enhancing human rights, and providing spaces for people's right to peaceful assembly and freedom of association, and the cases of arbitrary detention occurring in Cuba," Ban told reporters.

Dissidents, international human rights groups and Washington have expressed concern at reports of increased harassment and detentions of Cuban government opponents in the days before and during the summit. The Cuban government officially considers dissidents to be traitors in service of foreign interests and out to undermine its sovereignty.

Tuesday's session of heads of CELAC states began with a minute of silence to remember the late Venezuelan President Hugo Chávez, who succumbed to cancer last March.

Chávez, an outspoken U.S. foe, was a driving force behind CELAC's creation in 2011. It was conceived as an alternative to the Washington-based Organization of American States, which suspended Cuba's membership in 1962 shortly after Fidel Castro's revolution.

Proponents argued the OAS has historically served Washington's interests rather than those of the region, and even Latin American allies of the United States have participated enthusiastically in CELAC.

OAS Secretary-General José Miguel Insulza attended the summit as an observer, believed to be the first visit by a secretary-general to Cuba since its founding in 1948.

"The integration of Latin America is a strategic project. ... CELAC does not impede bilateral relations within and outside of the region. On the contrary, it strengthens them," Brazilian President Dilma Rousseff said in an evening address.

In his wide-ranging speech, Castro touched on the risk that global climate change poses to the region, especially low-lying Caribbean islands. He expressed solidarity for Argentina's claim to the British-controlled Falkland Islands, known in Spanish as the Malvinas; for Puerto Rican independence; and for Ecuador in its legal battle with U.S. oil company Chevron.

He also criticized the 52-year-old U.S. economic embargo on Cuba as well as American surveillance targeting the communications of foreign heads of state, companies and individuals. The threats of outside interference, military invasion and coups remain present, Castro said.

Fidel Castro, who retired as president in 2008, received visits from Rousseff, President Cristina Fernández of Argentina and Jamaican Prime Minister Portia Simpson Miller on Sunday and Monday.

He also met for 55 minutes with Ban, who described the former leader as "spiritually alert" and physically strong.

Ban's office said they talked about conflicts in Syria and Africa, food security, nuclear proliferation and Millennium Development goals.

Ban later addressed the summit leaders and praised their emphasis on reducing poverty and inequality.

"Your vision is one of a great diversity. This diversity is a strength that should be respected and nurtured. ... When CELAC is stronger, the United Nations is stronger," he said.

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