The US today accused three members of anti-American Venezuelan president Hugo Chavez's inner circle of aiding Colombian rebels by supplying arms and helping drug traffickers.
Washington also expelled Mr Chavez's ambassador as a diplomatic clash intensified.
State Department spokesman Sean McCormack condemned the expulsions this week of the American ambassadors to Venezuela and Bolivia. He said the US would kick out the Venezuelan even though Mr Chavez had announced last night that he was withdrawing his ambassador.
"This reflects the weakness and desperation of these leaders," Mr McCormack said of Mr Chavez and the embattled Bolivian president, Evo Morales.
McCormack suggested that the expulsion of the US ambassadors was meant to distract attention from the countries' regional and domestic difficulties.
Mr McCormack also warned: "No country has ever improved the well-being of its citizens by antagonising neighbours and refraining from fruitful integration with the world's democracies."
Mr Morales began the diplomatic spat by expelling the US ambassador on Wednesday - US officials responded by kicking out Bolivia's envoy to the US. Mr Chavez, who has been a political patron for Mr Morales, followed suit on Thursday. "Clearly he's worried about his protege," Mr McCormack said of Mr Chavez.
Mr McCormack added: "The charges levelled against our fine ambassadors by the leaders of Bolivia and Venezuela are false - and the leaders of those countries know it."
Separately, the US Treasury Department announced sanctions against Hugo Carvajal Barrios and Henry Rangel Silva, both chiefs of Venezuelan intelligence agencies. A former government minister, Ramon Rodriguez Chacin, was also named. The officials have served as Mr Chavez's most trusted security chiefs.
The Treasury said that the three helped the narcotics trafficking activities of the Revolutionary Armed Forces of Colombia, or FARC, describing the leftist group as a narco-terrorist organisation.
General Carvajal helped protect drug shipments passing through Venezuela, Treasury said, and provided the FARC with weapons and official government identification documents to ease travel in and out of Venezuela.
Mr Rangel allegedly aided the FARC in its drug trafficking and "pushed for greater cooperation" between the government and the rebels, the Treasury said.
The agency said Mr Rodriguez Chacin was the "main weapons contact for the FARC" within Mr Chavez's government. It said he held "numerous meetings with senior FARC members," including one at Venezuela's presidential palace in late 2007, and also tried to "facilitate a US$250m (€176m) loan from the Venezuelan government to the FARC in late 2007".
Adam Szubin, director of the Treasury Department's Office of Foreign Assets Control, said in a statement, that the "designation exposes two senior Venezuelan government officials and one former official who armed, abetted and funded the FARC, even as it terrorised and kidnapped innocents".
At the State Department, Mr McCormack said the sanctions had been in the works for some time and are unrelated to the diplomatic dispute.
Signs of FARC links to Venezuelan military intelligence chief General Carvajal surfaced earlier this year in documents on laptops seized from a bombed Colombian rebel camp in Ecuador.
In one 2007 message, the rebels' main go-between with the Chavez government said General Carvajal would help "get us 20 bazookas".
Mr Rodriguez Chacin stepped down on Monday as justice minister, saying he was leaving for personal reasons but continues to be a "revolutionary" and hopes to serve in another capacity. The specific reasons for his departure have not been explained.
A close ally to Mr Chavez, Mr Rodriguez Chacin was the president's primary contact with the FARC in talks on freeing hostages during the past year, and has for years been Mr Chavez's leading go-between with the rebels.
Critics have accused Mr Rodriguez Chacin of being too close to the Colombian rebels, and he was recorded in a video during one hostage release telling guerrillas, "we're paying attention to your fight".