By Lisandra Paraguassu and Anthony Boadle

BRASILIA South American presidents are gathering in Brasilia on Tuesday for their first summit in almost a decade at the invitation of Brazil's leftist leader Luiz Inacio Lula da Silva, who aims to regain his country's active role in regional affairs.

Ideological divisions undermined a previous attempt at regional cooperation called Unasur created by leftist presidents in 2008 that floundered when several countries elected right-wing governments, creating diplomatic fissures on the continent.

The invited presidents from all 12 of the continent's sovereign states, except Peru, will debate ways to coordinate on fighting climate change and high inflation in a region where poverty and hunger are on the rise.

"We won't decide anything at tomorrow's meeting, it is just about discussing possibilities," Lula told a news conference on Monday with Venezuelan President Nicolas Maduro, on his first visit to Brazil in eight years.

Lula said the leaders did not have to recreate a new Unasur but could come up with a different sort of organization.

"The main idea is that we need a bloc to work together on economic, investment and environmental issues. We need to learn to talk to each other," he told reporters.

Maduro is hoping the South American countries will unite in calling on the United States to lift its sanctions against Venezuela, which he and Lula assailed at their news conference.

Lula's return to office this year has brought a restoration of diplomatic ties between Brasilia and Caracas that had broken down under far-right former President Jair Bolsonaro, who banned Maduro from entering Brazil.

Brazilian officials organizing the summit said it was designed to keep political divisions from hindering cooperation.

"We are aware that there are ideological differences between the countries, but Lula wants to reactivate regional dialogue based on the common denominators the countries have," said Gisele Padovan, Secretary for Latin America and the Caribbean at Brazil's Foreign Ministry.

"The aim of this initiative is to unite all the countries of the region once again," she told reporters on Friday.

Unasur was set up during Lula's previous presidency, along with the leftist leaders of Venezuela and Argentina at the time, Hugo Chavez and Cristina Kirchner.

But its last meeting was in 2015, as divisions began to paralyze the group and South American diplomacy was marked by governments split between left and right, especially after the impeachment of Lula's successor in Brazil, Dilma Rouusseff.

In 2019, as the region's political pendulum swung the other way, the right-wing bloc ProSur was set up by then-presidents of Chile and Colombia, Sebastian Piñera and Ivan Duque. Also present were Brazil's Bolsonaro and Argentina's Mauricio Macri, along with conservative leaders of Ecuador, Peru and Paraguay.

That group has also lost steam as elections swung several of those governments back to the left.

(Reporting by Anthony Boadle; Editing by Brad Haynes and Shri Navaratnam)