State Department Mark Toner says USA officials are reviewing the details of an nearly 20-year-old lawsuit that led the Venezuelan government to seize a General Motors factory in the South American country.
The Maduro government's seizure of US -based General Motors' sole factory in Venezuela is likely to add to Tillerson's worries.
Speaking at a pro-government rally in the capital, Caracas, on Wednesday, Maduro called opposition leader Julio Borges a "coward", as quoted by The Washington Post, but also said that all the sectors of the opposition who were willing to engage in dialogue were invited to do so.
Opposition leader Henrique Capriles called for mass protests today (Thu) to force new presidential elections and the release of jailed opposition politicians.
Fears of violence spiked this week after Maduro said he would increase the size of a citizen militia that supports the government to 500,000 members and give each cadet a gun.
A demonstrator wearing a gas mask walks engulfed in a cloud of tear gas fired by riot police during an opposition march against Venezuelan President Nicolas Maduro in Caracas on April 19, 2017.
Socialist officials dismissed the opposition marches as efforts to destabilise the government, pointing to barricades of burning trash mounted by protesters and vandalism of public property.
On Monday, 11 Latin American countries, including Brazil, Argentina and Mexico, called on Venezuela's government to respect the constitutional right to peaceful protest. It has also delayed local and state elections.
(AP Photo/Fernando Llano). A police officer guides an armored vehicle during clashes with anti-government protesters in Caracas, Venezuela, Wednesday, April 19, 2017. "Today the people stood by Maduro!" he said, adding that more than 30 "terrorists" had been arrested.
Brian Ellsworth of Reuters, speaking to us by Skype from Caracas, said tensions have been building.
Wednesday's marches underscored the widening political rifts in the country, where the opposition has accused Maduro of creating a dictatorship in the last few years.
"We're going to go on struggling", she said Wednesday, "because the one who tires, loses". So far, at least two people have died. "We'll see who tires out first".
The third fatality was a national guardsman killed by a sniper during protests in Miranda state, according to human rights ombudsman Tarek Saab.
GM can seek compensation and damages for its lost plant in several different worldwide venues, said Nigel Blackaby, a lawyer at the Freshfields Bruckhaus Deringer law firm, which has battled Venezuela in several high-profile cases in global courts.
Government supporters and security forces on Wednesday succeeded in blocking marchers from reaching certain parts of the city, according to observers.
Some unhappy Venezuelans also steer clear of protests, fearful of violence, cynical that marches can bring about change, or too busy looking for food amid the recession. Thousands of Maduro's supporters held a counter-rally in central Caracas. The opposition says Maduro has morphed into a dictator and accuses him of letting state forces and gangs of armed thugs violently repress demonstrators as he resists opposition pressure for him to quit.
The former president, Hugo Chavez, died in 2013 leading Maduro, then vice president, to be promoted into power.
"We are concerned that the government of Maduro is violating its own constitution and is not allowing the opposition to have their voices heard, nor allowing them to organize in ways that expresses the views of the Venezuelan people", Secretary of State Rex Tillerson told reporters on Wednesday.