They exchanged barbs over the abrupt end last week to his efforts to free captives held for years by the Revolutionary Armed Forces of Colombia (Farc), including three Americans and Ingrid Betancourt, a French-Colombian politician.

 

"I'm telling the world: As long as President Uribe is president of Colombia, I will not have any type of relations with him or with the government of Colombia. I cannot," Chavez said at a political rally near the border.

 

Uribe on the other hand has refused to withdraw his ambassador to Caracas, urging Chavez not to be emotional.

 

"Heads of state should think not about their personal rage and their own vanity, but more about the need to respect the people they represent," he said.

 

The ongoing dispute is the worst between the two countries since 2005 when Chavez withdrew his ambassador after bounty hunters snatched a Colombian rebel in Caracas and dumped him over the border to be arrested by Colombian police.

 

Other spats 

 

"Heads of state should think not about their personal rage and their own vanity"

Alvaro Uribe, Colombian president

Last weekend Chavez also froze relations with Spain in a dispute that started after he called an ex-prime minister a fascist, and was told to "shut up" by Spain's King Juan Carlos.

 

The Venezuelan president, a vocal anti-US socialist, has recalled ambassadors from Mexico and Peru in the past, although there was little impact on trade.

 

On Sunday, Chavez will face his toughest vote battle since taking office in 1999.

 

Polls suggest that he may lose a referendum on constitutional changes that would allow him to run for re-election indefinitely.