Venezuelan opposition leader Maria Corina Machado insisted Monday that elections cannot proceed without her name on the ballot, as the United States announced it was reimposing some sanctions against the country following her disqualification.

Venezuela's Supreme Court, loyal to President Nicolas Maduro, upheld on Friday a 15-year ban on Machado holding public office.

It also confirmed the ineligibility of a possible opposition stand-in -- two-time presidential candidate Henrique Capriles.

The 56-year-old Machado described the ruling as "grotesque" and showed no sign she would bow out of the race.

"Nicolas Maduro will not choose the candidate of the people, because the people have already chosen their candidate, period," Machado told her supporters.

"I received the mandate of almost three million Venezuelans" in an opposition primary in October, she said. "We are going to win and they must prepare to lose."

"They cannot hold elections without me," she added.

Last year, Maduro's government and the opposition reached a mediated deal in Barbados to hold a free and fair vote in 2024 with international observers present.

That agreement saw the United States ease sanctions against the South American country, allowing US-based Chevron to resume limited oil extraction and leading the way to a prisoner swap.

But on Monday, White House spokesman John Kirby said members of the Maduro government "haven't taken those actions" promised in Barbados, and he spoke of Washington's "options with respect to sanctions."

Hours later the US Treasury announced it was reinstating some sanctions on Venezuela and its mining sector.

According to a statement by the Treasury's Office of Foreign Assets Control, any US companies doing business with Venezuela state-owned mining concern Minerven have until February 13 to complete a "wind down of transactions" with the firm.

US Senate Foreign Relations Committee chairman Ben Cardin said he was "deeply disappointed" with the Venezuela court's ruling and said Maduro was behaving "like dictators around the world" to avoid competing in a fair election.

"As Machado's absurd disqualification clearly violates the Barbados Agreement, the US must reimpose related sanctions until a clean election is assured," Cardin said in a statement.

- EU 'very concerned' -

The Supreme Court said Machado would remain disqualified "for being involved... in the corruption plot orchestrated" by former opposition leader Juan Guaido.

Guaido, now in exile, was recognized for years by dozens of countries as the legitimate president of Venezuela after a 2018 election that saw Maduro inaugurated for a second successive term despite widespread fraud claims.

Maduro has not confirmed he will seek a third term, but is widely expected to do so. No date has yet been set for the election, which is expected in the second half of 2024.

The European Union said in a statement Monday it was "very concerned" by the disqualification of Machado and Capriles.

"Decisions intended to prevent members of the opposition from exercising their core political rights can only undermine democracy and the rule of law," it said, urging "the full implementation of the Barbados Agreement."

Last week, Maduro said the deal was "mortally wounded" after government authorities claimed to have foiled numerous US-backed plots to assassinate him.

The government insisted Monday that all was above board.

"Those who wanted to appeal appealed and also pledged to respect the outcome," said Jorge Rodriguez, head of that government delegation involved in talks with the opposition.

And senior official Diosdado Cabello said there would be "free, transparent, credible, universal, direct and secret elections without the presence of the United States, without the presence of the OAS," the Organization of American States.