Venezuelan President Hugo Chavez said Monday that reconciliation is impossible with Colombia's president as the two leaders traded stern warnings in an escalating diplomatic crisis that threatens trade ties between the South American neighbors.

Chavez said Sunday he is putting relations ''in the freezer'' after President Alvaro Uribe ended the Venezuelan leader's role mediating with Colombia's leftist rebels. That announcement drew a strong rebuke from Uribe, who said Chavez's actions suggest he wants to see a ''terrorist government'' run by leftist rebels in Bogota.

The spat is the bitterest yet between Chavez and the U.S.-allied Uribe, who in the past have sought to cultivate cordial ties despite their deep ideological differences.

It could have serious economic consequences. The two countries are major commercial partners, with $4.1 billion in trade last year, about two-thirds of that in Colombian exports to Venezuela.

Neither leader announced any concrete plan, but Chavez said economic relations will be hurt as a result of Uribe's actions, which he called ''a spit in the face.''

Relations with Colombia have reached their ''most serious crisis,'' Chavez said in a televised interview early Monday. While diplomatic channels may remain open, he said, ''not reconciliation because it's impossible now. When it reaches these levels between two heads of state, it's impossible.''

''We'll have to wait for a new government in Colombia we can talk with,'' Chavez said on state television. ''I hope it arrives sooner than later.''

He said Venezuela will be on alert to potential military threats from Colombia as well.

Chavez was responding to Uribe's decision Wednesday to end Chavez's role mediating preliminary talks with the Revolutionary Armed Forces of Colombia, better known as the FARC. The talks aimed to free rebel-held hostages including three Americans and Ingrid Betancourt, a French-Colombian seized in 2002 while campaigning for Colombia's presidency.

Uribe's government said Chavez broke the conditions of his involvement by directly contacting the chief of Colombia's army. On Sunday, Uribe questioned Chavez's motives.

''Your words, your attitudes, give the impression that you aren't interested in peace in Colombia, but rather that Colombia be a victim of a terrorist government of the FARC,'' he said in the town of Calamar. ''The truth is President Chavez, we need a mediation against terrorism, not people who legitimize terrorism.''

Chavez has suggested that FARC rebels could eventually put down their guns and join politics. But Uribe said addressing Chavez: ''If you are spreading an expansionist project in the continent, in Colombia this project will make no headway.''

Uribe also suggested the socialist leader might be looking to stir up conflict to boost his image ahead of a referendum Sunday on constitutional changes that would let him run for re-election indefinitely.

The confrontation is a sharp break for two leaders who have often appeared together smiling and speaking of their ''sister nations.'' Just last month, they opened a natural gas pipeline between their countries.

But on Monday, Chavez said Uribe is serving his ''masters'' in Washington.

''Uribe's mask has fallen off,'' he said. ''It's the voice of the oligarchy and the voice of the U.S. empire. ... They could build him a statue in Washington now.''

Chavez said Uribe has often assured him U.S. military aid -- ''spy planes ... military bases, CIA batallions'' -- is strictly for domestic operations.

''I hope that's the case, although we have to be alert,'' Chavez said. ''I hope Uribe doesn't go mad and let himself be taken by that warmongering conceit and try to use, or let our sister Colombia be used, as a destabilizing factor against Venezuela, carrying out orders from the U.S. empire.''

''If he were to try to do it, all the worse for him,'' Chavez said. ''I think he wouldn't last very long in the government. I think it would fall.''

The row comes amid another similar dispute with Spain. Chavez has demanded Spanish King Juan Carlos apologize for telling him to shut up during a summit in Chile. And Chavez said Sunday, ''Until the king of Spain apologizes, I'm freezing relations with Spain.''

Uribe replied, taking a jab at Chavez's oil-funded foreign aid: ''President Chavez, the truth is you can't set fire to the continent like you do, talking one day against Spain, the next day against the United States ... and speaking of imperialism when you want to create an empire based on your budget.''