Venezuela's deputy United Nations military attache, Col. Pedro Chirinos, said in a video on social media that he recognized opposition leader Juan Guaido as the country's interim president, increasing pressure on President Nicolas Maduro.
Fifty countries, including Germany, have recognized Guaido as interim president since he openly challenged Maduro.
Some 250,000 people are expected at Friday's concert in the Colombian border town of Cucuta that organizers say will raise about $100 million to buy food and medicine for Venezuelans suffering widespread shortages.
"I really think the concert is inconvenient, given the tensions at the moment".
Meanwhile, Venezuelan opposition leader Juan Guaido set out on Thursday to personally collect US-supplied food and medicine stockpiled in Colombia.
Guaido has said aid distribution is Venezuela's chief priority.
Two other world leaders may attend, organizer Fernan Ocampo told reporters in Cucuta earlier on Wednesday, without naming them.
This trip will be Pence's fifth trip to Latin America as Vice President.
Opposition leaders led by Juan Guaido are vowing to bring in U.S. supplies of emergency food and medicine to dramatise the country's hardships under Mr Maduro, who has said the country doesn't need such help. Caracas would not allow such aid into the country, Maduro said, saying the country was coping with its difficulties and that United States "concerns" over Venezuela's humanitarian crisis were "fabricated by Washington over the last four years to justify intervening in our country". "So I think, Jorge, there has got to be a free and fair election", Sanders asserted. "He says that it's a democracy, people are not suffering, and it's just not true", Branson said. (AP) Opposition leaders led by Juan Guaido are vowing to bring in U.S. supplies of emergency food and medicine to dramatise the country's hardships under Mr Maduro, who has said the country doesn't need such help.
The border with Brazil - which along with Colombia is one of the main potential avenues for aid delivery - would be "completely and absolutely" closed from 8pm (00:00 GMT) until further notice, Maduro said.