Secretary of State Condoleezza Rice and Venezuela's foreign minister fired verbal broadsides at each other Monday over the closure of a key opposition television station in Venezuela.

Rice protested the shuttering of Radio Caracas Television, RCTV, calling it Venezuelan leader Hugo Chavez's "sharpest and most acute" move yet against democracy as thousands of university students marched in Caracas to protest.

Venezuela's top diplomat, Nicolas Maduro, then accused her of hypocrisy, unacceptable meddling in his nation's affairs and compared the U.S. detention center at Guantanamo Bay, Cuba, and secret prisons elsewhere to something not seen since "the time of Hitler."

Earlier, thousands of Venezuelan students marched in protest of the station's removal, chanting "freedom!" and "we aren't afraid!" as they paraded toward the Supreme Court.

It remains unclear whether their protests will maintain momentum, or whether they will coalesce into a major political force.

The dispute between Washington and Caracas took center stage at a gathering of foreign ministers of the Organization of American States, a meeting intended to focus on environment and development issues.

Rice told reporters en route to Panama that Chavez's closure of RCTV was just the latest and perhaps strongest attack on democracy since coming to power in the late 1990s and pursuing an increasingly anti-U.S. and leftist line.

At the meeting, she urged the OAS to send its secretary-general, Jose Miguel Insulza, to Venezuela to look into the closing of the station and deliver a full report on his findings.

"Freedom of speech, freedom of association and freedom of conscience are not a thorn in the side of government," Rice told the ministers. "Disagreeing with your government is not unpatriotic and most certainly should not be a crime in any country, especially a democracy."

Maduro, speaking after Rice, reacted angrily, saying her comments were an "unacceptable intervention is the internal affairs of a nation, and that is why we reject it."

"Venezuela is asking for respect," he said. "We demand respect for our sovereignty."

Maduro defended the decision not to renew RCTV's license as "democratic, legal and fair" and accused the United States of repeated violations of human rights, including at the U.S.-Mexico border where immigrants "are chased and hunted like animals" and at Guantanamo Bay, where he said terrorism suspects are being "held hostage."

Rice requested and was given time to rebut Maduro's comments, saying, "Issues of democracy and the defense of democracy are never inappropriate" and defending the United States' record on press freedom, noting that media outlets routinely criticize the U.S. government.

"I am quite certain that it would be difficult for any commission to debate more fully, to criticize more fully the policies of the United States government than is done every night on CNN, on ABC, on CBS, on NBC and on any number of smaller channels," she said.

"That is the point of press freedom," Rice said. "In a democracy the citizens of a country should have the assurance that the policies of their government will be held up for criticism by a free and independent press without the interference of their government.

"The citizens of the United States have that assurance, I sincerely hope that the citizens of Venezuela will have that assurance as well," she said to loud applause before leaving the room before Maduro could reply.

In response, Maduro lashed out at Rice for leaving the room and kept to his criticism of Guantanamo. "There are hundreds, a disastrous thing comparable only to the time of Hitler, when there were clandestine jails with prisoners who didn't have names. It's monstrous," he said.

He suggested that journalists from a new state-funded Venezuelan public television station TVES should be allowed to interview detainees at Guantanamo and renewed a call for a commission to look into the abuses of Latin American immigrants to the United States.

"The United States and its government, sooner rather than later, will have to learn to respect the sovereignty of our governments, our people, our new Latin America, our new Caribbean that will never again become a colony," Maduro said, also to applause.

Brazil, Honduras, Guatemala and Chile have expressed support for RCTV and on Monday in Panama, newspapers and a consortium of media groups published ads, saying, "Without freedom of expression, there is no liberty, not in Venezuela or any other part of the world."

Protests have surfaced at most of Caracas' public and private universities since the opposition-aligned channel RCTV was forced off the air May 27 by Chavez's decision to not renew its license. The demonstrations have spread to other universities nationwide.

In Caracas on Monday, about 10,000 university students marched through the capital, chanting "Freedom! Freedom!" and handing white carnations to police officers as they paraded toward the Supreme Court, where they presented magistrates with a document demanding the government respect freedom of expression.

The populist Chavez has been a source of deep concern for the United States since he took power in the late 1990s and steered the country down an increasingly leftist, anti-U.S. path with close and strong ties with Washington's arch-foe in the Americas -- Fidel Castro of Cuba.