Venezuelan students protested in chains outside the Cuban Embassy in Caracas on Thursday, condemning what they say is the Caribbean nation's meddling in their country's affairs while President Hugo Chavez remains on the island undergoing cancer treatment.

Some students exchanged shoves with police in anti-riot gear outside the embassy. Protesters sang the Venezuelan national anthem, wearing chains and cords wrapped around their bodies and bound with locks in a representation of what they view as a government beholden to Cuba's interests.

"We demand respect for our sovereignty. We don't want any more Cuban meddling in Venezuela's affairs," said Gabi Arellano, a student leader.

Arellano said the students are also protesting against Chavez's long absence and the way it has been handled by the government. "We can't continue in uncertainty and adrift," she said.

Top opposition leader Henrique Capriles on Thursday also criticized the lack of information about Chavez's condition, speaking separately at a news conference.

Chavez remains in Havana undergoing unspecified treatments following his fourth cancer-related operation on Dec. 11. He has hasn't been seen or spoken publicly in more than two months.

The group of about 20 university students protested outside the embassy throughout the day.

When some tried to approach the embassy to hand over a document summarizing their protest at about noon, they were pushed back by National Guard troops. Seven protesters were reported detained for several hours, and later were released.

The National Journalists Association reported that three journalists were roughed up by National Guard troops while covering the protest.

The students laid mattresses on the ground and said they planned to stay and keep protesting. Some traveled from other parts of the country to join the demonstration.

Gabriel Velasquez, one of the protesters, said that if Chavez doesn't appear in public again soon, an "absolute absence" should be declared and a new election should be held to replace him. Another student, Ricardo Fernandez, said he came from southern Bolivar state to join the demonstration because "we really don't know if he's alive or he's dead."

"We need for them to tell us the truth," Fernandez said.

While the protest was under way, Capriles questioned the president's long silence at a news conference.

Capriles asked why, if a president can sign documents to approve measures such as a newly enacted devaluation, "he's not going to be able to speak to the country."

The opposition leader said that if Chavez doesn't appear publicly, "then you're lying. Then it isn't true that the president talks and signs. You're forging (his) signature. You're all lying to Venezuelans using the president's signature," Capriles said.

Vice President Nicolas Maduro has traveled repeatedly to Havana, and Maduro has shown on television documents signed by Chavez. On Wednesday, Maduro said that Chavez is now undergoing "extremely complex and tough" treatments, which he didn't specify.

Medical experts consulted by The Associated Press have said the government's recent account of "systemic medical treatment" could mean various types of chemotherapy or drug treatments, depending on the type of cancer.

The 58-year-old president has been undergoing cancer treatment in Cuba on-and-off since June 2011. He has had tumors removed from his pelvic region, and has also undergone prior rounds of chemotherapy and radiation treatment.

Since December, the government has provided regular updates, though there have been fewer updates in recent weeks, and often with only vague descriptions of Chavez's condition.

During the president's two-month silence, government opponents have been accusing Cuban leaders of wielding influence behind-the-scenes in guiding the decisions of Chavez's socialist government.

Throughout his presidency, Chavez has viewed Fidel Castro as a friend and mentor. The relationship has been reinforced with commercial ties, as Venezuela has shipped oil to Cuba in exchange for the services of thousands of doctors, nurses and sports trainers who have come to the country to work in neighborhood clinics and community centers.

Capriles has been critical of what he calls giveaways by Chavez to allies such as Cuba.

He also condemned a currency devaluation that took effect this week, saying the government now should raise the minimum wage to compensate working-class Venezuelans as the country struggles with 22-percent inflation.

"The whole country, we're going to get organized to put the brakes on this package," Capriles said, referring to the economic measures.

He said only the government benefits from the devaluation by turning its dollar-denominated oil earnings into larger sums of local currency, but that regular citizens suffer.

Maduro rebuffed Capriles' criticisms saying the governor should get back to work in his own state. The vice president also said Capriles seems "obsessed" with being a presidential candidate again. Capriles lost to Chavez in the country's October presidential election.