By MICHAEL WEISSENSTEIN, Associated Press

HAVANA (AP) — A third round of negotiations over the restoration of full diplomatic relations ended after a day of talks, Cuban and U.S. officials said Tuesday. Hours later, Cuban President Raul Castro delivered a toughly worded attack on the United States for levying a new round of sanctions on his country's closest ally, Venezuela.

Neither Cuba nor the U.S. provided details on whether progress was made toward a deal on reopening embassies in Washington and Havana.

The two countries have been trying to strike an agreement on embassies before presidents Barack Obama and Raul Castro attend the Summit of the Americas in Panama on April 10-11.

Cuba's Ministry of Foreign Relations said the talks took place "in a professional atmosphere" and "the two delegations agreed to maintain communication in the future as part of this process." Jeff Rathke, a U.S. State Department spokesman, said that "the discussion was positive and constructive and was held in an atmosphere of mutual respect."

But Castro later delivered a searing defense of Venezuela at an emergency meeting of leftist Latin American governments called in response to U.S. sanctions levied on seven Venezuelan officials last week. In announcing the move, the U.S. declared Venezuela a threat to U.S. national security.

Washington has asserted that the Venezuelan sanctions wouldn't affect its negotiations with Cuba, but Castro made clear in Caracas that he sees the two issues as linked.

He described Obama's declaration of detente with Cuba as a recognition that a U.S. policy of hostility to Latin American socialism had failed.

"Nonetheless, the spokesmen of his government have made clear that the objective remains, only the methods have changed," Castro said. "The U.S. must understand once and for all that it's impossible to seduce Cuba or intimidate Venezuela."

Neither Cuba nor the U.S. said Tuesday whether they had resolved any of the obstacles to reopening embassies, which include Cuba's continuing presence on the U.S. list of state sponsors of terrorism and Cuba's objections to U.S. diplomatic contact with dissidents on the island.

The secretive atmosphere was a striking contrast to previous discussions about U.S.-Cuban detente. After two earlier meetings, U.S. and Cuban diplomats engaged in wide-ranging exchanges with reporters from both nations that were broadcast on Cuban state television.

Cuban state media dedicated virtually no coverage to Monday's talks, focusing instead on statements of support for Venezuela.

Despite the heated rhetoric, Julia Sweig, an expert on U.S. relations with Cuba and Venezuela, said early Tuesday there was no sign the increasingly strained U.S. relationship with Venezuela was affecting the warming of relations with Cuba.

"What's so interesting is that it doesn't seem to derailing the bilateral process, which is exactly as it should be," said Sweig, a senior research fellow at LBJ School of Public Affairs at the University of Texas, Austin.

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Associated Press writers Andrea Rodriguez in Havana and Matthew Lee in Washington contributed to this report.

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Michael Weissenstein on Twitter: https://twitter.com/mweissenstein