Colombia on Monday accused Ecuador and Venezuela of colluding with its FARC rebel foes in an escalating regional crisis sparked by a cross-border raid.
Ecuador angrily rejected Bogota's allegations and severed diplomatic relations with its neighbor, citing "a succession of events and unfriendly accusations," according to a message to Bogota from Quito obtained by AFP.
Venezuela, meanwhile, ordered the immediate expulsion of Colombia's ambassador and embassy staff, "in defense of homeland sovereignty and the dignity of the Venezuelan people," its foreign ministry said.
Bogota said computer records from a FARC camp inside Ecuador it bombed on Saturday proved the allegations, and would present them to the United Nations and the Organization of American States (OAS), which is due to meet on the matter on Tuesday.
Colombian police chief General Oscar Naranjo told reporters the data suggested the rebel Revolutionary Armed Forces of Colombia (FARC) had acquired 50 kilograms (110 pounds) of uranium.
The allegations came as Ecuador and Venezuela ordered troops to mass near their borders with Colombia, triggering fears of a conflict between two leftist governments and the United States' main southern ally.
Quito and Caracas said the ordered deployments were defensive, to parry any further incursions by Bogota.
The two countries also strongly denied having ties to the FARC, which is regarded as a "terrorist organization" by Colombia, the United States and the European Union for its tactics of making money from kidnappings and drug trafficking.
Colombian Defense Minister Juan Manuel Santos said the bold Saturday raid on the FARC base located just inside Ecuador landed "the heaviest blow ever dealt" to the rebels, killing their number two commander, Raul Reyes, 59.
But Venezuelan President Hugo Chavez, a socialist firebrand ideologically sympathetic to the Marxist-inspired FARC, reacted by ordering some 6,000 troops, tanks and warplanes to the border with Colombia in case of a raid on Venezuelan soil, where FARC bases have been reported.
Ecuadoran President Rafael Correa, a close Chavez ally, said he was sending his own forces to the northern frontier with Colombia, and ordered both his ambassador to Bogota and Colombia's ambassador in Quito to return home.
"Ultimate consequences" may result from Colombia's weekend raid, Ecuador warned.
Correa late Monday said Colombia's cross-border raid had blocked "advanced stage" negotiations with FARC for the release of 11 hostages, including French-Colombian politician Ingrid Betancourt -- FARC has released six hostages since Janaury.
Despite the bellicose statements, by late Monday there were no signs of deployments that could herald an armed clash.
Colombia said its military remained focused on the FARC not the country's borders, while President Alvaro Uribe issued a statement saying "the revelations on the accords between the FARC terrorist group and the governments of Ecuador and Venezuela will be made known" to the OAS and the UN.
The United States, which has backed Colombia in its decades-long fight against the FARC, said it supported Bogota's offensive against the "terrorist" guerrillas but called for resolving tensions with Colombia's neighbors through diplomacy.
Bogota accused Quito and Caracas of abetting the rebels, saying that documents and photographs taken from the FARC camp just inside Ecuador showed contacts between Reyes and Ecuadoran Interior Minister Gustavo Larrea, it said.
This indicated "a connivance, a sort of association between the government of Ecuador and the guerrillas," Santos charged.
Police chief Naranjo said Venezuela was implicated through a record of a payments totaling 300 million dollars to the rebels from Chavez.
But Naranjo said an alleged rebel account of the acquisition of 50 kilograms of uranium was especially worrying.
Venezuelan Interior Minister Ramon Rodriguez Chacin shot back calling Colombia's accusations "absolute fabrications," adding that Reyes' computers were being manipulated by Colombia to justify a "preventive war" against Venezuela.
Larrea in Quito admitted meeting with Reyes in January to talk "exclusively about the hostage issue," he told reporters.