WASHINGTON (Reuters) - The U.S. government on Thursday warned Venezuelan President Nicolas Maduro of consequences for what it called “egregious” acts of intimidation, and said Russia and other countries should cease “last-minute looting” of oil and gold.

Supporters of President Nicolas Maduro attend a rally in support of the state oil company PDVSA in Caracas, Venezuela January 31, 2019. REUTERS/Manaure Quintero NO RESALES. NO ARCHIVES.

Juan Guaido, Venezuela’s self-proclaimed interim president, said on Thursday that agents from a feared special police unit had visited his home.

“Such acts of intimidation are seen as very serious, very egregious by the United States,” a senior U.S. administration official told reporters on a conference call. “There will be consequences for those engaged in such acts, they will be held accountable and they will be missing this unique opportunity to move on.”

Speaking on condition of anonymity, the official urged Venezuelan military officials to accept Guaido’s offer of amnesty if they backed his claim. So far, the Venezuelan military has remained loyal to Maduro.

The United States and most other Western nations have backed Guaido’s push for a transition and new elections. But Russia and China, among others, are supporting Maduro.

Washington also warned Maduro, Russia and other international players against making deals for Venezuelan commodities like gold and oil.

The arrival of an unusual Russian plane in Caracas this week sparked rumors, denied by Russia, that gold was being shipped out the country.

Venezuela is selling gold from its central bank vaults to the United Arab Emirates in coming days in return for euros in cash, a source said.

The U.S. government wants Venezuela oil company PDVSA’s U.S. subsidiary, Citgo, to keep operational despite tough new sanctions it imposed earlier this week.

“Our goal is to ensure that Citgo remains viable, but to make sure that Maduro and his cronies are not able to loot Citgo in the way that they’ve been looting it for years,” the official said, adding that the U.S. was also looking at further economic sanctions.

The official said Maduro and a dozen other Venezuelan officials were standing in the way of a political transition, and the U.S. government was open to conversations about how to help them leave the country.

But the U.S. government rejects recent suggestions that Uruguay, Mexico, or the Vatican should play a mediating role between Maduro and Guaido, the official said.

“We explicitly reject any talk about any type of effort that would allow Nicolas Maduro to usurp or, maintain himself in power, or be a political player in that regard,” the official said.

Maduro, who has been in power since 2013 and began a second term earlier this month after disputed elections last year, has said Guaido’s actions are an attempt at a U.S.-backed coup.