Caracas: Venezuela is starting to block billions of dollars in Colombian imports and investments under orders from President Hugo Chavez, threatening economic havoc in both nations in response to a Colombian military attack on rebels hiding in Ecuador on last Saturday.

Chavez and Ecuadorean President Rafael Correa demanded international condemnation of Colombia's US-allied government, while Chavez predicted a sharp fall in the US$6 billion in annual Colombia-Venezuela trade.

"We aren't interested in Colombian investments here," Chavez said. "Of the Colombian businesses that are here in Venezuela, we could nationalise some."

He said Venezuela will search for other countries like Ecuador, Brazil and Argentina to replace products imported from Colombia. Noting that Colombia traditional supplies food to Venezuela, he said now "we can't depend on Colombia not even for a grain of rice."

Though Venezuelan officials express confidence they will quickly find replacements for Colombian goods, government critics says the move is bound to worsen shortages of basic foods from milk to chicken that were an annoyance in Venezuela well before a dispute that has ballooned into one of South America's most serious diplomatic crises in years.

Chavez and Correa warned on Wednesday that a regional diplomatic crisis would not end without clear international condemnation of Colombia's government for the deadly cross-border strike against leftist rebels.