Henrique Capriles, who challenged President Nicolas Maduro for the presidency in 2013, had his passport cancelled at the airport as he tried to leave the country, according to news reports.
Capriles was on his way to New York to meet with U.N. High Commissioner for Human Rights Zeid Ra'ad al-Hussein when Zeid tweeted this:
The U.N. said the high commissioner would instead meet Friday afternoon with Capriles' lawyer, who will be in New York and would present Zeid with "a report."
"We find the rising tensions in Venezuela very alarming, and incidents like that involving Mr. Capriles yesterday are unlikely to help reduce tensions," Zeid's spokesperson, Rupert Colville, told reporters in Geneva on Friday.
Opposition supporters throw stones into an air base while clashing with riot security forces during a rally against President Nicolas Maduro in Caracas, Venezuela, May 18, 2017.
The high commissioner's office also expressed concern about the treatment of protesters in Venezuela, which has been rocked by more than six weeks of anti-government street demonstrations aimed at removing President Maduro from power. At least 42 people have been killed in the unrest.
Colville told reporters the human rights office is troubled by allegations of the excessive use of force by security forces, saying international human rights standards must be respected.
"We are very concerned by reports that people who have been detained in the context of the protest are being brought before military tribunals," Colville added, saying they should be dealt with in civilian courts. He also urged protesters to use peaceful means.
The U.N. Security Council had its first briefing on the situation on Wednesday, at the request of the United States.
'In Venezuela, we are on the verge of [a] humanitarian crisis," U.S. Ambassador Nikki Haley said in a statement. "Peaceful protesters have been injured, arrested and even killed by their own government. Medicine is unavailable, hospitals lack supplies, and it's become difficult to find food."
New US sanctions
On Thursday, the Trump administration announced plans to impose new sanctions on members of the Venezuelan Supreme Court for stripping the opposition-led congress of all power earlier this year. Among those targeted is Maikel Moreno, the president of the pro-government Supreme Court, which issued the ruling in late March. The ruling was later partially reversed amid international criticism, but it sparked the protest movement currently destabilizing the country.
President Donald Trump called the situation in Venezuela a 'disgrace to humanity,' and said the deadly political crisis is possibly the worst of its kind in 'decades.'
The threat of new sanctions comes as Maduro, a socialist, is facing increasing international pressure to hold elections. He has repeatedly accused the United States of leading an attempt to overthrow his government.
The president's political opponents are demanding that he schedule long- delayed elections, release political prisoners and permit the delivery of humanitarian aid. The demonstrations and counter-demonstrations have escalated since the socialist leader's call earlier this month for a new constitution.