John Kerry, the US secretary of state, earlier criticised the government's actions to quell the protests. "The government's use of force and judicial intimidation against citizens and political figures ... is unacceptable and will only increase the likelihood of violence," he said in a statement, adding: "This is not how democracies behave."
For years, Venezuela has been wracked by searing divisions over its 15-year-old Socialist revolution, embraced by many of the poor who have benefited from the diversion of oil profits into social programmes, but anathema to much of the middle and upper classes. In the past two weeks, frustation at the rampant inflation, chronic food shortages and some of the world's highest murder rates has erupted into opposition protests - igniting the country's long-seething political and class tensions and drawing radicals from both sides into running street battles. In the epicentres of the violence, burning barricades, molotov cocktails and tear gas are now a daily sight.
It is a crisis with high international stakes. Venezuela sits atop the world's largest proven supplies of oil and is the leader of a strong leftist alliance in Washington's backyard. The government has also alleged the involvement of Alvaro Uribe, the former president of neighbouring Colombia, a key US ally in the region with which Venezuela has a fractious relationship.
On Thursday, the government ordered paratroopers into the border city of San Cristobal, the birthplace of the protests where protesters have been engaged in fierce battles with security forces. The internet was cut off and residents said they were living in a "war zone", with the town fully occupied by the army and military helicopters and planes flying overhead.
From the fray has emerged Leopoldo Lopez, a key opposition figure who has taken the lead in a hardline protest movement under the slogan "The Exit", meaning Mr Maduro's departure from power. Declared "the face of fascism" by the leftist leader, Mr Lopez is now languishing in a military jail outside Caracas on charges of arson, damage and criminal gatherings, accused of orchestrating protest violence in order to justify a coup d'etat.
On Friday the wealthy 42-year-old Harvard economist urged the protesters not to give up. In a note from prison released through his wife, he said: "To the police, soldiers, prosecutors and judges: do not obey unjust orders, do not become the face of repression.
"To the youth, to the protesters, I ask you to stay firm against violence, and to stay organised and disciplined. This is everyone's struggle."
Mr Lopez and his supporters insist the government is to blame for the protest violence, claiming they are tacitly endorsing radical Chavista armed groups to attack opposition protesters. They also complain of excessive violence by security forces, who have used tear gas, buckshot and water cannon to disperse protesters, and allege that some of those detained have been tortured.
In a country where fact is often difficult to distinguish from rumour or even outright fabrication, some claims are almost impossible to verify. The government's vice-like grip on televised media means the protests, and the opposition, have been largely kept off Venezuelan screens. Mr Maduro has also expelled a Colombian broadcaster and threatened to throw out CNN, accusing it of a "propaganda war"and, according to the network, refusing or revoking press credentials for several of its journalists. Instead opponents have taken to social media, where manipulated videos and images abound.
But on Friday, Mr Maduro acknowledged that police officers had fired shots at an opposition protest in which three people died last week. He announced he was investigating whether there were "plotters and conspirators" within his government, claiming that the same firearm had been used to kill both a student protester and a pro-government activist. Investigators are also examinng a case of a protester allegedly "raped with a gun" after being arrested in the city of Valencia.
While opposition leaders insist they are not agitating for an overthrow, some of their supporters acknowledge they have lost patience with attempts to unseat the government through the ballot box. They accuse the ruling Socialists of electoral fraud, and note that almost half of the Venezuelan electorate are reliant on state jobs or subsidy programmes, with heavy pressure to vote for the government.
Alberto Delfante, an opposition supporter in Caracas, told the Telegraph: "I don't believe this government will ever surrender democratically. If they become very threatened they could simply announce a dictatorship, what would we do then?
"What we're seeing now is very much like what it looked like in 2002 (the coup d'etat). I'd like to see this government forcibly removed, but we don't know what the reaction of the chavistas would be."
Dr Fred Mills of the Council on Hemispheric Affairs, a US based think tank, told The Telegraph that "the "exit" strategy has clearly been translated on the streets into a golpista (coupster) strategy by a considerable segment of the opposition." But he suggested they were miscalculating "the balance of forces" in the country, saying that unlike in 2002, the military leadership was not inclined to a coup and the Chavista base were on high alert.
But Carlos Cardenas of IHS Country Risk said the most likely scenario was that protests continued to escalate, drawing in some of the poorer areas which have so far seen only sporadic involvement.
"This scenario would lead to eventual fractures within the PSUV (Socialist) party and the military, with Maduro not being able to contain the associated violence. Should this scenario take place, the risk of Maduro being ousted due to a military intervention would increase significantly."