Buenos Aires/La Paz - These are difficult times for US diplomacy in South America. Bolivia and Venezuela expelled the US ambassadors from their countries, in aggressive and often abusive, televised announcements by their presidents.

It started with Evo Morales, Bolivia's first indigenous president and an ally of Venezuela's Hugo Chavez. In a dramatic television appearance Wednesday he said: "Without fear of the empire, I declare today to the Bolivian people that Mr Goldberg, the ambassador of the United States, is persona non grata."

The radical move came as Bolivia reels from violent riots and an escalation in the conflict between Morales and five eastern, opposition-controlled provinces who oppose redistribution of oil revenues to help the poor.

The president, who used Chavez's term "empire" to refer to the US, accused US Ambassador Philip Goldberg of supporting the opposition and their separatist aims.

Argentina's President Chavez was quick to follow late Thursday, by ordering the US ambassador to leave his country within 72 hours in an abusive televised rally. He accused Washington of trying to kill him and told Americans to "go to hell."

In a diplomatic tit-for-tat, the United States on Thursday declared Bolivia's ambassador an unwanted person, and on Friday expelled the Venezuelan ambassador and sanctioned two Venezuelan officials close to Chavez for aiding Colombian FARC rebels.

"The charges leveled against our fine ambassadors by the leaders of Bolivia and Venezuela are false and the leaders of those countries know it," US State Department spokesman Sean McCormack said Friday.

The increasingly ugly rows come, coincidentally, on the 35th anniversary of the coup in Chile, believed to be backed by the CIA, where socialist president Salvador Allende was replaced by dictator Augusto Pinochet on September 11, 1973.

A joke doing the rounds in the region is also a statement on the strained relations between the US and some Latin American countries. "Why is there never a coup in the US? Because there's no US ambassador there."

Even Argentine President Cristina Fernandez de Kirchner has been miffed with the US. A trial in Miami is linked to a suitcase that was discovered last year in Buenos Aires with 800,000 dollars - the illegal funds were believed to be campaign money from Venezuela to help Kirchner win the 2007 presidential election.

Bolivia has opted to lash out against the US, which gives it more development aid than any other country does, serves as Bolivia's largest export market and is a major provider of counter-narcotics assistance.

Washington believes that Bolivia's move will prejudice the interests of both countries, undermine the ongoing fight against drug-trafficking, and have serious regional implications.

Notwithstanding those aid and economic ties, there is a feeling in the region that the United States is against Bolivia's leader or any others who, like Morales, have nationalized key industries, dragged their feet in the war against drug smuggling and preferred to be photographed with Iranian President Mahmoud Ahmadinejad than US President George W Bush.

It's not clear what's at the heart of the charges against Goldberg, but some are questioning whether Morales has done the country a favour or a harm.

With five of the country's nine provinces pushing for autonomy with increasing violence - as many as 14 people have died in clashes since Thursday - it's not clear what will be accomplished by kicking out the US ambassador.

In Venezuela, Chavez's rhetoric came booming across with his characteristic bluster as he threatened - as he was many times in the past - to cut off oil sales to the US. Venezuela has one of the world's largest oil reserves outside the Middle East.

On Friday, the State Department's McCormack said Chavez and Morales were acting desperately to cope with increasing domestic opposition to their leadership.

"This reflects the weakness and desperation of these leaders," he said, adding they were trying to deflect attention from their domestic woes. "That's part of the playbook." (dpa)